What do snails eat?

I found these snail in a bush by a garden there are 10 or 11 of them? i think there just the common "garden snail" they were on the underside of leaves and were in a type of hibernation. the were kind of stuck on surafe with dried slime. how long will this do this and stuff right now i have them in a lil aquarium with a few peices of lettuce and and gr and a small cotton ball with water on it. 3 of the eleven have awoken and 1 of the 3 has gon back into it hibernation thingy. sooo how do i car 4 snails? lol?