Michelle Obama munched a baby turnip, dug up giant sweet potatoes and snipped pumpkins off the vine as she teamed up with local schoolchildren and world-class chefs for a fall harvest day in the White House garden.

One hulking sweet potato weighed in at 4 pounds on its own, drawing an admiring stare from the first lady.

"You guys have witnessed the first White House pumpkins," she told the children as they loaded up wheelbarrows and weighed in their haul.

Mrs. Obama later posed for a group photo with the harvest team, and at first prompted the children to smile and say "cheese." But then she had a better idea, declaring, "Let's say 'veggies!'"

After the kids finished their harvesting, they were put to work once again, washing the produce and then slicing and dicing vegetables for a fresh garden salad made just for them.

The White House kitchen team got some help from world-renowned chefs Daniel Boulud and James Kent, representing the United States in the 2011 Bocuse d'Or cooking competition, known informally as the Olympics of cooking.

Boulud quizzed the schoolkids on what to do with turnips and then told them, "We can make a good soup with that."

The garden has produced 1,600 pounds of food this year, used to feed the first family and White House guests and for donations.