Unnamed spotting

That's what I found out also, which amazes me. Closely-tied to Agaricus, resembling a stalked puffball, and it thrives in the desert. Very unique mushroom, and it's funny how they all pop up at once after monsoon rains. You can really see that the little kids love 'em; after a couple of days I find them either stepped on, the tops kicked off and landing in some faraway place, but I think it's a decent way to spread the spores anyways!

Thanks for the lesson in desert mushrooms. When I looked it up, it was said that it is more closely related to the Shaggy Mane Coprinus comatus than with the puffballs. I like how it turns into the same black spore mess, but being in the desert it's dry rather than inky wet.

No, it's definitely a Desert Shaggy Mane, Podaxis pistillaris. They split open and become a small pile of dark spores carried off by the wind, and given the location and environment it's growing in, there's little room for doubt. Here is an example of the mature specimen, growing under the same conditions: http://www.projectnoah.org/spottings/735...

I'd be inclined to think this is a Coprinus. If it has a black spore print and ages to an inky mess then that's what it likely is.