Collection location: Santa Rosa, Sonoma Co., California, USA [Click for map]
Two aged specimens found in cultivated, regularly watered soil. Spore print was white. No annulus or sign of one was present. Gills are free. Smells like grocery store mushrooms.
Based on a guess that the veil had dropped off by the time I arrived on the scene I decided this mushroom was some form of Leucoagaricus. L. barssii is the only one with a fibrillose pileus, hence my ID.
Both Arora and Mykoweb call this infrequent in our area.Furthermore, Mykoweb states that it would prefer drier conditions in our area than in the Northwest. Nonetheless, it seems to be the best fit that I can find. Any thoughts?