If you have time, I've made sugar cookies in the shape of a glove (Wilton's) & bought bubblegum in the shape of baseballs (I found that at a bulk candy store). The frosting keeps the gum stuck to the glove cookie.

You could also make a kid's trail mix (anything you might want to throw together - peanuts/M&Ms/cereals etc).

I've also brought ice cream bars or popsicles (timing is critical on this one).

Popcorn is a favorite.

I usually get Squeeze Its with juice in it - the kid's like the shape, too.

Good Luck!