Prince Harry and Meghan honor Princess Diana on 23rd anniversary of her death

Prince Harry and Meghan, the Duke and Duchess of Sussex, made a rare public appearance in Los Angeles on Monday, the 23rd anniversary of the death of Harry's mother, Princess Diana.

The Sussexes paid tribute to Diana, who died in a Paris car crash on Aug. 31, 1997, by planting forget-me-nots, the late princess's favorite flower, in the garden of a local preschool.

When Harry and Meghan wed in 2018, the couple included forget-me-nots in Meghan's wedding bouquet to honor Diana, who was just 36 when she died -- Harry was 12 years old when his mother died.

"Oh, they'd be thick as thieves, without question," Harry has said about his late mom and Meghan, adding that he thought Princess Diana "would be over the moon" about their relationship.

Harry and Meghan, who moved from London to California earlier this year, spent Monday volunteering at Preschool Learning Center, which provides early-childhood education to children from low income families.

The Sussexes worked alongside students in the school's garden and spent time talking with them about nature and healthy eating, according to the Assistance League of Los Angeles, which runs the preschool.

Harry and Meghan were seen in photographs kneeling down to interact with the preschool students at their level and getting their hands dirty in the garden, just as Princess Diana was known to do at engagements with kids.

Harry has remembered Diana as "one of the naughtiest parents" who "smothered" him and his brother Prince William with love.

"She was our mum. She still is our mum. And of course, as a son I would say this, she was the best mum in the world," Harry said in the 2017 documentary "Diana, Our Mother: Her Life and Legacy." "She smothered us with love, that's for sure."

"She was very informal and really enjoyed the laughter and the fun," Prince William said in the same documentary. "But she understood that there was a real life outside of palace walls."