The first thing that comes to my mind is Pinewood Derby cars. (This is kinda a brain storming idea so I didn't think it all the way through.) Maybe bring a piece of track and some old cars. In 8 years as CM, I have collected 5 or 6 unclaimed cars. You could also bring derby rockets or raingutter reagatta boats. How about a "Knot Board", Den Doodle, patch collection, hiking stick w/ medallions on it and a belt with sports and academic loops on it. (Ooooh, shiney things!!)
A snack you could provide is a no-cook s'more. Get the little paper mini cupcake holders, they're about the size