Agrocybe firma is a decomposer that grows on dead hardwood logs in wooded areas and can be found summer through fall. It is mostly distributed west of the Great Plains, but can also be found on the Northeast coast, Europe, and undoubtably more places.

It has a dark, firm cap without lines at the margin. Gills that are narrowly attached to the stem that start white-colored then turn dull brown. The stem is distinctly ornamented with scale-like tufts of white fibrils that turn brown with age. Annulus and volva are absent. It can be found fruiting in clusters or, rarely, alone.

September 21st, 2023 Field Notes - Indian Cave State Park

• Growing scattered and clustered (locally abundant) on well-decayed hardwood log in low moist mixed oak/hickory woodland draw.
• Caps dull brown, slightly velvety and hygrophanous.
• Lamellae tan, crowded with frequent partial gills.
• Stipe similarly colored as gills, fibrulose (iridescent) especially at apex, and adorned with removeable scales on the bottom 3/4.
• Aggressive white rhizomorphs.
• Smell: not distinctive
• Taste: bitter