One of many edible puffball species. Closely related to Calvatia gigantea, it tastes quite similar although it is more prone to turning sour before the spores start to turn brown. It has no stalk, just a mass of spores inside a brown nubbed skin. As it ages, the spores change color from white to brown. In many ways it closely resembles Lycoperdon, except it never developes the hole at the apex which Lycerperdon uses to release spores.
Like C. Gigantea, Calvatia bovista makes a good tofu substitute when young and pure white inside. Slice and sautée on medium high heat with a bit of butter until it begins to brown, then add it to whatever dish you please. Make sure that it has not started to turn sour. As soon as any of the interior starts to change color from pure white to yellow-tan or brown, toss it. Also, be very careful not to confuse C. Gigantea with the "egg" of an Amanita. Such a mistake could be deadly. Check very carefully by cutting through the center of the fruiting body, looking for any signs of the formation of an embryonic gilled mushroom. A giant puffball has an undifferentiated mass of white spores inside, an Amanita egg will have the ghosted pattern of a baby mushroom inside.