Rather small and typically dark; hemispherical to convex caps are smooth and satiny, dark brown to reddish-brown in colour and fading with age. It can be very variable in colour depending on weather; darker, sticky and shiny when wet.. Stipe dark brown with a powdery look.   Grey brown gills with paler edges, blackening as spores mature.   Spores are smooth and black. 

other Mottlegills (Panaeolus) and  the Brown Mottlegill or Mower's Mushroom (Panaeolina foenisecii) may be found in similar habitats.

microscope

chrysocystidia with amorphous yellow inclusions

Photograph from top down, in side-view and underneath to show gills; note habitat and substrate. This can be a difficult fungus to identify and we recommend that spores are examined, or that it is verified by an expert from a specimen before submission to NatureSpot.

lawns, roadside verges, mown grasslands

May to November 

Widespread

Status in Leicestershire and Rutland not known.

https://www.first-nature.com/fungi/panaeolus-fimicola.php