Puff ball. Not sure if that is an "official" name. After they dry out, they puff out a cloud of spores if you step on them.
I just pulled one out of my yard today before I mowed. It was solid!!! If you guys have any of these in your yard, do not throw them away. They are awesome are to eat!
Puff balls are edible, and tasty. Finch, I shy away from any "toad stool" mushroom like that. They make me too nervous to eat as I dont know the difference between them and I know a lot of them are at least mildly toxic.