I haven't had a child leave for school but when children leave my dc, I like to give them some pictures from their time here. I only give the ones that are only of their child. I keep the group photos and display around my dc before putting them in photo albums. I usually buy a toy/book/puzzle of something that I know they like. I did gift baskets this summer filled with ice cream toppings. It was something they could enjoy as a family.

For an older child leaving for school, I would likely do the pictures and then a book and a clothing item.