Lucky you! Those are Giant Puffballs, Calvatia gigantea. There's nothing to confuse them with, once they get that big! You're also lucky that they are still solid inside. If they are all pure white, they are good to eat. They are too old to eat, if their insides are yellowish or any other color besides bright white. I cut them into 1-2-inch thick steaks, and then dredge them in an egg-wash and flour. And then fry them. So good!