The cap variable in colour, from pinkish- to yellowish-brown, convex and sometimes with a slight umbo or depressed centre. It has radial fibrils. Gills are quite widely spaced, inkish or yellowish, and the stem is yellow/brown with dense whitish hairs towards the base.  Taste is acrid or peppery, and smell is sour or vinegary.  

Photograph from top down, in side view and from underneath to show gills and full length of stipe.  Note habitat and substrate

In leaf or needle litter, mixed woodlands

Autumn.

Widespread and fairly frequent in Britain.

Fairly frequent in Leicestershire and Rutland.