These are generally tiny agarics (fungi with cap, stem and gills) which grow on wood, forest floors or grassland. There are about 120 species in the UK, most of them all but impossible to identify without experience, a microscope, a serious book such as The Genus Mycena: Fungi of Northern Europe vol. 5, and a very great deal of patience. A handful are common and relatively easy to identify as they will have 'tricks' such as producing red or white latex when broken or smelling strongly of nitric acid. No Mycena spp are edible.