I am asked this question a lot so here is a list of the different things I add to my worm bins:
In no particular order:
Rabbit manure
Shredded cardboard
Mulched leaves
Pulverized eggshells
Chipped/mulched tree limbs
Comfrey leaves
Select fruit and veggie scraps
Used coffee grounds
Used tea bags
Shredded newspaper (very little)
Azomite powder
Granite dust
Old shredded bills or financial information