Psathyrella piluliformis, commonly known as the clustered brittlestem, is a species of agaric fungus in the family Psathyrellaceae.
It produces fruit bodies (mushrooms) with broadly convex caps measuring in diameter. The caps are chestnut to reddish brown, the color fading with age and with dry weather. Fragments of the partial veil may remain on the cap margin, and as a wispy band of hairs on the stipe.
The closely spaced gills have an adnate attachment to the stipe. They are initially tan until the spores mature, when the gills turn dark brown. The stipe is 2âÂÂ7 cm tall and 3âÂÂ7 mm wide, white, smooth, hollow, and bulging at the base. The spore print is dark brown, sometimes purplish.
Similar species include Psathyrella carbonicola, P. longipes, P. longistriata, P. multipedata, P. spadicea, and Parasola conopilus.
Fruiting occurs in clusters at the base of hardwood stumps.
The species is considered edible but of low quality, with fragile flesh and being difficult to identify.