Any kind of shellac will do as long as it says on the container that it's "non-toxic, safe for children's toys & food area". I didn't realize it earlier but it can apparently be purchased at the local hardware store for pretty cheap.

BULLS EYE SHELLAC is one such shellac that's safe for use on things children might put in their mouths, which basically means its food grade. It says on the can that it's approved by the FDA. The FDA allows you to use it on kitchen utensils such as wooden spoons and other things you might put in your mouth.