I agree about the food allergy issue. I have kids on my team with nut, egg, etc, allergies, and I think if you choose to bring a food item, something like hard candy or a lollipop is probably better. I think bringing items to swap is fun for the kids, but to be honest, I have to say I also think that it can be kind of wasteful, all that stuff. We talked about this as a team. If there is an item that can serve the purpose of getting the kids to interact, but also be a useful item or an item with information on it, that seems to make more sense to me. For example, one year, my team made little cards (about twice the size of a business card) with information about their research project on it. They came up with it themselves, we printed it on cardstock, cut them on the paper cutter, and it was very inexpensive.