Conserving herps,
In response to your snail question, you'll probably find that almost any type of omniviorous or carnivorus turtle/tortoise will eat them. My box turtle loves to go foraging about in our front yard for snails. When he finds them he simply pulls them out of their shells and bon apetite! Any turtle that will eat earthworms (most aquatic and semiaquatic species and some tortoises) will at least try snails. If you do plan to feed them to any of your chelonians, keep them for a week or so in a container with lettuice (of other food stuff) to be sure that all impurities have passed out of their systems. This is due to the fact that the snails you have in your yard were probably in all of the surrounding yards at some point or another and could have picked up who only knows what. I hope this helps ya, good luck!
EMWhite