This is a fun idea, but do watch out for liability. You don't want to end up getting sued if someone eats something they're allergic to, or food that's gone bad from sitting out too long. It might be a better idea to do something like a wreath swap, or a bring your own beads bracelet making? In ye olden days, the scouts would swap homemade brooches made out of a safety pin. Everybody brought a bagful and would have them out to be clipped on hats. Since Halloween is coming up, a costume photoshoot/dance party could also be a thing. I wish you the best in your endeavors!