When President Reagan invited Queen Elizabeth II to spend time with his family, he was determined to win her over.

It was 1983 and Britain’s reigning monarch took up the president’s offer of a 10-day semiprivate tour of the West Coast, which was a "long-held ambition" of hers. It was during her trip that she and husband Prince Philip visited the Reagans’ California ranch where she feasted on Mexican food for the first time, a favorite of Reagans.

It was a far cry from the game meats the queen, a longtime sportswoman, consumed behind palace doors.

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Queen Elizabeth II having a grand dinner with Ronald Reagan

President Reagan introduced Queen Elizabeth II to his favorite cuisine. (Tim Graham Photo Library)

"There were enchiladas, chiles rellenos, refried beans, tacos, rice and guacamole," David Charter, author of "Royal Audience," told Fox News Digital.

"She absolutely loved it, especially the refried beans," he chuckled. "She told one of Reagan’s guys, ‘I really love this meal, especially the used beans.’ She hadn’t quite gotten the name of it, but she certainly enjoyed it and made it well-known to everyone there."

"Royal Audience" explores the special relationship between the U.S. and the British royal family over the years. Charter described how Reagan was one of the late queen’s favorite presidents to befriend over the years.

Queen Elizabeth and Ronald Reagan on horseback

President Reagan and Queen Elizabeth II bonded over their mutual love of horses. (Diana Walker)

"They developed such a closeness, especially over horseback riding," Charter said. "She would tell you she liked every president she met, but they did share a close bond, especially over their mutual love of horses."

"He was so affable and hospitable to her," Charter said. "That was extremely important to him. They got along terrifically. She also got along wonderfully with [first lady] Barbara Bush. She was similar to the queen, being a matriarch who had to look after a big family on the public stage with perhaps a slightly wayward son who needed guidance, at least as a young man. And Barbara Bush loved dogs – that was a [guaranteed] subject to win the queen over."

Queen Elizabeth and Prince Philip standing with the Bush family during a reception

Prince Philip, first lady Barbara Bush, Queen Elizabeth II and President George H.W. Bush arrive at a White House state dinner on May 14, 1992. (Arnie Sachs/CNP)

Darren McGrady, a former Buckingham Palace chef, previously told Food & Wine that the queen opted for a more traditional meal. According to the outlet, she enjoyed cucumber or salmon sandwiches every day during afternoon tea. She would have Earl Grey tea with no cream and sugar. Being health-conscious, she frequently passed on pasta, potatoes and other carbs.

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The Reagans greeting Queen Elizabethj II

President Reagan and first lady Nancy Reagan welcome Queen Elizabeth II to their ranch at Rancho Del Cielo, California. (Ronald Reagan Library)

According to the outlet, the queen had four meals on a typical day, including afternoon tea. For breakfast, she preferred a bowl of Special K with a boiled egg alongside a cup of tea. Other meals throughout the day consisted of a compound salad, pheasant, venison, other lean meats, and fish, as well as a pudding and sliced fruit for dessert.

But it was in America where the queen could let her hair down – in her way.

"When she visited America, she found her personal sense of freedom," Charter said. "Now, I’m not saying she was running around in jeans and going to rock concerts. But in terms of being queen, she had a freedom in America that was unheard of in Britain."

Queen Elizabeth II watching the game from the stands

Queen Elizabeth II is shown talking to Wilson H. Elkins, president of Maryland University, during the third quarter of the Maryland-North Carolina game she attended. (Getty Images)

One of the queen’s highlights from her royal trips to the U.S. was visiting a supermarket in Maryland in 1957. For the occasion, she wore a $15,000 full-length mink coat. According to the book, she wanted to see "how American housewives shop for food."

It was at Giant supermarket in West Hyattsville where the queen surprised "bemused afternoon shoppers." She loved the grocery carts, exclaiming, "How nice that they can bring their children along!"

"Large supermarkets were relatively unknown in Britain, so she really wanted to visit one," Charter said. "So, very hastily, a trip was arranged. The manager was shocked. Here’s the queen wearing a full-length mink coat with her husband, Prince Philip, as housewives in pin curls are pushing their kids around in carts. She’d never seen anything like it before. She was just amazed."

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Queen Elizabeth II at a supermarket

Queen Elizabeth II was fascinated by supermarkets. (Justin Tallis/Pool/AFP)

"Philip noticed a rack of aluminum foil when someone explained to him that that’s what housewives used to wrap their food in before putting it in the oven and cooking it," Charter continued. "He had no idea what he was looking at. He was stunned. Meanwhile, the British media were just as stunned because the queen had never really mingled with ordinary folk. But here she was, making a spontaneous trip to a store and chatting with shoppers. ... She really had a personal interest in America and how people lived there. But really, she enjoyed coming to America."

When it came to presidents and first ladies meeting the queen, the fascination was mutual. But not every encounter was smooth sailing.

It was in 1961 when the queen opened the doors of Buckingham Palace to President Kennedy and his wife, Jackie.

Queen Elizabeth and Prince Philip standing with the Kennedys

President Kennedy, Queen Elizabeth II, first lady Jackie Kennedy and Prince Philip are shown during the Kennedys' visit to England. (Getty Images)

"It was a semiprivate visit because Jackie’s sister was having the christening of her child in London, and of course, the government and the palace wanted the Kennedys to have dinner at Buckingham Palace," said Charter.

"’The Crown’ made a lot of drama about how the queen was jealous of the attention Jackie received,’" he said, referring to the Netflix series. "The truth is, Jackie was bursting onto the international scene. She was a few years younger than the queen. She had just visited Paris where she bought the most fashionable looks. And she had already made her mark as a fashionable spouse who spoke French fluently."

Book cover for royal audience

David Charter has written a new book titled "Royal Audience: 70 Years, 13 Presidents - One Queen's Special Relationship with America." (G.P. Putnam's Sons)

"Jackie had beauty, youth and chicness. That could make anyone jealous," Charter continued. "But that’s not what made the evening awkward. What happened was Jackie wanted her sister (Lee Radziwill) and brother-in-law to come to dinner. It was a 50-person dinner, quite a small dinner really for Buckingham Palace. But Jackie’s sister was divorced, and her husband was on his third marriage. In the 1960s, this was an absolute no-no in Britain. No divorcees were allowed to go to an event at the palace, even an informal one. Jackie was asked who else she wanted present. She said she would like to see Princess Margaret, the queen’s more exciting sister, and Princess Marina, an aunt of the queen who was also very fashionable; she even had a color named after her: Marina blue."

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Jackie Kennedy waving next to her sister Lee

Jackie Kennedy is seen here with her sister, Lee Radziwill. (Getty Images)

According to Charter, diplomats worked frantically as the palace objected to Jackie’s requested guests. In turn, Jackie objected to the objection. Reportedly, it was Kennedy who stepped in and told the palace "not to bother about us, we’re here unofficially." While the palace relented on the Radziwills, the two royals Jackie wanted to meet were not, which was viewed as "a nasty surprise" to the puzzled first lady.

"The queen had her revenge," Jackie allegedly told writer Gore Vidal. "… No Margaret, no Marina, no one except every commonwealth minister of agriculture that they could find. I think the queen resented me. Philip was nice but nervous. One felt absolutely no relationship between them. The queen was human only once."

Society photographer Cecil Beaton wrote in his diaries that Jackie allegedly felt "they were all tremendously kind and nice, but she was not impressed by the flowers, or the furnishings of the apartments at Buckingham Palace, or by the queen’s dark-blue tulle dress and shoulder straps, or her flat hair."

Jackie Kennedy smiling and standing next to Queen Elizabeth II

Queen Elizabeth II is seen here with first lady Jackie Kennedy after they had dinner at Buckingham Palace. (Getty Images)

For the evening, Jackie wore an ice-blue, sleeveless silk evening dress from New York boutique Chez Ninon. The London Evening Standard wrote, "Jacqueline Kennedy has given the American people one thing they had always lacked – majesty."

"I think the episode of ‘The Crown’ was a little overdone," Charter said. "But it was a very awkward evening."

The queen had hoped to meet Kennedy again, but it never happened. The president was assassinated in 1963. He was 46.

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Queen Elizabeth greeting American children

Queen Elizabeth II is seen here greeting schoolchildren while walking from the White House on May 7, 2007. (Chip Somodevilla)

Today, Charter hopes his book will introduce a new side to the late queen.

"She made it part of a lifelong duty to keep Britain and America as close as possible," he said.