Purple-spore Puffball, Calvatia cyanthiformis, is closely related to the Giant Puffball, C. gigantea, which can grow larger and does not have the sterile base the Purple-spored Puffball does. The Giant Puffball is also more common in the north, but I have found both here. The Purple-spored Puffball is also related to the Brain Puffball, C. craniformis, which looks very similar but prefers a woodland habitat. C. craniformis has yellow-brown (rather than purple) spores when mature.
I found this one growing solitary near where I found Vascellum curtisii and Lycoperdon perlatum earlier in the year.
Harvest the Purple-spored Puffball when it looks like a loaf of bread inside and out and enjoy.