WAZZZATT???? (Lawn toadstool)
This is Calvatia sculpta, the sculptured puffball. It is a relative of mushrooms, but does not have gills. When the spores mature to a brown, powdery mass, it opens and they are dispersed.
Much appreciated! I assume it's harmless? We like having it around.
Bob and Kathy
Yes, it is harmless.