Obama said she had "all this protocol buzzing in my head" when she was due to be picked up by Her Majesty in person, and driven by her to Windsor Castle.
"And so the Queen says "just get in, sit wherever" and she's telling you one thing and you're remembering protocol and she says, "Oh it's all rubbish, just get in".
"Speaking in London on Monday, Obama said that the possibility of falling over at a public appearance is always on her mind".
"She's smart and amusing and honest", she said.
Former US president George HW Bush dies at age 94
John Major, British Prime Minister from 1990-1997 said Bush "saw America's obligation to the world and honored it". - The George Bush Presidential Library and Museum in College Station captures a full and fascinating life.
Mrs Obama added that her husband had always had a great affection for the Queen, saying: "Barack is so incredibly fond of Her Majesty and I won't go into his fangirling but I think it's because she does remind him of his grandmother Toot, she's smart and amusing and honest". He is a huge fan for sure, ' she said.
During a sell-out talk at London's Southbank Centre to promote her new autobiography Becoming, Obama recalled feeling anxious about royal etiquette ahead of her and President Obama's last visit to Windsor Castle, when they were picked up by the Queen and Prince Philip in their auto.
She will speak alongside Nigerian novelist and moderator for the evening, Chimamanda Ngozi Adichie, whose work has examined post-colonialism and feminism. "It doesn't go away, that feeling that you shouldn't take me that seriously".
She said: "I touched her".
The pair also discussed the current political situation in the U.S. and the idea of progress in civil rights.
India 4th Highest Carbon Dioxide Emitter, Emissions May Grow by 6.3 %
Most of that growth can be traced to an exceptionally hot summer and cold winter. These regions represent 40 per cent of global carbon emissions.
First Lady Michelle Obama and US President Barack Obama (L), are greeted by Queen Elizabeth II and Prince Philip, Duke of Edinburgh (R) as they arrive to Buckingham Palace on May 24, 2011 in London, England. "It just means that it's hard, what we are trying to do is shift culture". "I know too many young couples who struggle and think that somehow there's something wrong with them".
Obama's memoir is filled with other moments of honesty for which she's being praised, particularly with respect to how much her words of truth have the power to help other women.
Michelle and Barack Obama with the Queen in 2016.
She said: "It was a lot more of a personal interaction and honestly she is so believable because I feel like she really humbles herself, she really talks about things that we can relate to, she even spoke about doubt and how sometimes she also doubts herself and those are things that we can all relate to, no matter how accomplished we are".
Letrishka Anthony was 16 when Mrs Obama first visited Elizabeth Garrett Anderson School during her first year in the White House and is one of the school's alumni to join her on a visit to the campus nine years later.
‘I Love You, Too’: George H.W. Bush’s Final Words To Son
Eight years later, in accepting his party's nomination for president in 1988, Bush pleaded for a "kinder, and gentler nation". His passing ushers in almost a week of remembrances and tributes in Washington , where Bush will lie in state at the U.S.