Agaricus abruptibulbus (Peck)
Syn: Agaricus essettei (Bon)

This strongly flavescent  and almond scented species is frequent in the Bay Area and Marin County, but probably has a wider distribution. The common link between all my collections is Douglas Fir although that I have seen it in mixed stands with predominantly broadleaved species. It is very similar  to A. silvicola and some have synomyzed them. I see differences in the following aspects (1) larger spores, (2) more than 50% of the collections with an abruptly bulbous stem base and (3) discoloration that goes all the way to tawny.  Still, I see forms that integrate quite well and a critical study may only be able to reach conclusive results. For now for the sake of record-keeping I separate it from A. silvicola. The European authors have a similar taxon A. essettei (Bon) and they have synonymized A. abruptibulbous to it, but until things get cleared up it would make sense to use the American name. Other flavescent species with an almond odor in the local forests are A. albolutescens (different stature and lacks an emarginated bulb), A. smithii (looks different and fruits up North), A. summensis (also discolors tawny, but has a different stature) and A. spissicaulis (Møller).

Spores: 6-7.5 (8) x 4-5µ Peck's original description