This rotund little mushroom is Scleroderma citrinum, commonly known as the pigskin poison puffball (from here on referred to as PPP).
|Pigskin poison puffballs live near the bases or exposed roots of trees, especially oak, maple and conifers.|
PPPs are a very common mycorrhizal species, usually found at the bases of older trees (though sometimes young trees can have them as well), and often among exposed roots. (Mycorrhizal means they have a symbiotic relationship with plants, in this case trees).
As a child, this was my favorite mushroom. In late September and early October I would run around the neighborhood oaks and give each PPP I found a tentatively gentle squeeze. If it felt ready--less firm and slightly squishy--I would stand up, back off, and run two or three steps to jump on the mushroom as hard as I could, so that it would truly explode in a cloud of spores.