Meghan Markle and Prince Harry welcomed their first baby Monday and are celebrating another "first" this Sunday — Meghan's first Mother's Day as a mom. To mark the occasion, the royals' Instagram account posted a new photo of little Archie Harrison Mountbatten-Windsor.

Sussex Royal, the couple's official Instagram, posted a sweet image of Archie's tiny feet held by, what appear to be, Meghan's hand. Archie had only been seen once before, when the couple presented the infant to the press — and the world — Wednesday.

The baby appears to be posed in front forget-me-not flowers — which could be a nod to Harry's late mother, Princess Diana. The flowers were one of Diana's favorites, according to Vanity Fair. This isn't the first time the flowers have appeared during significant life events for the couple. Prince Harry also reportedly handpicked flowers from Kensington Palace's garden for Markle's wedding bouquet. The bouquet included forget-me-nots.

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The image's caption may also pay tribute to Diana. "Paying tribute to all mothers today — past, present, mothers-to-be, and those lost but forever remembered," said the post. "We honor and celebrate each and every one of you."

Princess Diana died more than 20 years ago in a car crash in Paris at age 36. Prince Harry was only 12 and Prince William was 15 at the time.

Princess Diana, pictured here with a young Prince Harry and William, in 1987. AP

The caption also included a quote from poet Nayyirah Waheed's work, "lands": "My mother was my first country; the first place i ever lived," the post reads.

While Sunday marks Mother's Day in America, as well as many other countries, the holiday is celebrated in March in the U.K., according to the BBC. So, it seems the Duchess will be able to celebrate two holidays next year, when Archie — who is seventh in line to the British throne — is nearly a year old.