It's my understanding that you might not want to do that. Corn snakes can satisfy all of their nutritional needs from mice and rats and I don't think they care about "variety" like you and I might. Also, if you offer your snake lizards and frogs it might never go back to eating mice and rats which I understand are less expensive than the lizard diet.
There are others on this forum whom I know feed their Corns baby chicks and other small critters, so they may have more information to offer than me.
Cheers,
Jason