I got a live plant with snail eggs on it, snauls haven't hatched yet. It does get cold in the winter so would they be ok in a 300 gallon pond (all the offspring except for four or five per tank, so about 20-30 being kept)?
Can you determine what kind of snails they are? If they are exotic snails, I wouldn't recommend putting them in an outdoor pond mostly because some would probably wander off and escape. Then you have loose exotic snails. I'm not sure if that would pose a large ecological threat where you are, but better safe than sorry. A lot of snail infestations in wild areas were started because it was assumed that escaped or released snails would never survive to breed. Here in Florida we have exotic apple snails (a.k.a. "Mystery snails") invading our wetlands, so please pardon my paranoia when it comes to aquarium snails getting loose.
Also keep in mind that if you have several snails per tank, soon they may start breeding (rapidly) and they become an infestation. Then you wind up having to kill most of them anyway just to keep their numbers under control.
I would definitely figure out what species they are first. If they are a species you like, then keep as many as you feel you should, but if they are an undesirable species and no one else wants them, you may have to dispose of them
. I know it sounds cruel and heartless to kill unwanted baby snails, but if they are a pest species then there is no way around it.
Or maybe you're lucky and they're trumpet snails or something cool like that, and your local pet store may take in the extra snails you don't keep. But in answer to your question, I would not put any kind of non-native snail in a pond of any size.