Former President Jimmy Carter often sent his mother to meet with foreign dignitaries and attend state funerals, but it wasn't until he started researching a new book about her life that he learned just what the woman known as "Miss Lillian" did on those visits.

"Mama had developed a reputation for expressing unorthodox opinions and not being constrained by any outside advice," Carter writes in "A Remarkable Mother," which chronicles Lillian's life from her birth in 1898 to her death from cancer in 1983. "The officials in the State Department were always quite nervous about what she would do or say that might violate protocol and damage relations between our government and that of the country she was visiting."

The book is constructed from diaries, letters and interviews with family and friends.

"It was a lot of fun for me to write," Carter said in a recent telephone interview with The Associated Press. "I learned a lot I hadn't known before."

One such tidbit? His mother, on visiting Rome, brushed aside prepared remarks and told the media she was happy to be there for three reasons, among them that she had "never met an ugly Italian."

Her blunt and unorthodox ways often embarrassed her peanut farmer-turned-politician son, who spent many White House press conferences answering questions about comments his mother had made the previous day.

"She would go on the Johnny Carson show, Merv Griffin show or even Walter Cronkite and just take over the program," Jimmy Carter said. "It was a problem for me because often I would be called on to comment on what my mother had said in a ridiculous give-and-take with Merv Griffin. I would just grin and bear it."

The book paints a picture of a woman charming enough to meet with foreign dignitaries and down home enough to prefer fishing over most any other activity.

She gave more than 600 public speeches both in the U.S. and overseas during her lifetime and befriended the likes of Shirley MacLaine, Frank Sinatra and Dean Martin.

She met Bob Dylan, Elvis, two Popes and a whole list of foreign presidents.

Jimmy, her eldest son, considered her his secret weapon during his 1976 presidential campaign.

"Since I ultimately defeated Gerald Ford by a very narrow margin, I think it's accurate to say had my mama not been out on the campaign trail, I probably would not have won," Jimmy Carter said. "By the time the other candidates woke to what was happening, they had already lost the election."

Even before her son became commander in chief, Lillian Carter was making social and political waves.

She was a nurse in the small town of Plains, Ga., often treating black families when such behavior was taboo in the racially divided South. She insisted black visitors enter through the front door when social customs dictated they use the back.

"It's important to show the American people what a superb American citizen might be ..." Carter said. "She was indomitable, she was courageous and she didn't yield to public pressure when she thought she was right."

In 2006, Jimmy Carter and his wife visited Vikhroli, India, where Lillian Carter had volunteered to serve in the Peace Corps at age 68, spending two years working with lepers. The couple was besieged by dozens of villagers telling stories about the Carter family matriarch, even though 40 years had passed since her stay there.

The former president reflects on the visit in the postscript of his new book: "Our hearts filled with pride and our eyes with tears, as we thought about how many other lives had been affected by my mother."