Gregarious or scattered in many different habitats, in lawns and open areas, under trees (both conifers and deciduous trees), among litter under Juniperus, among terrestrial mosses, on moss covered trunks, among fallen leaves and on fallen twigs. Summer to autumn. Widespread in the whole area. In Norway recorded all over the country.

Pileus 5-20 mm across, conical to broadly conical, parabolical or convex, sulcate, translucent-striate, hygrophanous, sometimes somewhat lubricous, glabrous, very variable coloured, pale yellowish, greenish yellow, olivaceous yellow,  pure yellow, yellowish with a brownish grey shade, grayish green, grayish with a yellow tinge,  darker at the centre, paler towards the margin. Odour indistinctive, raphanoid or somewhat nitrous. Taste mild. Lamellae 15-21 reaching the stipe, ascending, narrowly adnate, occasionally decurrent with a short tooth, dingy white to pale grey-brown, the edge citrine to deep yellow, less frequently pallid to whitish. Stipe 25-85 x 0.5-1.5 mm, hollow, fragile, equal for the greater part, somewat broadened below, terete, straight to somewhat flexuous, minutely puberulous all over, glabrescent, pale yellowish, greenish yellow, olivaceous green, grayish, paler above, darker below, yellow-brown to grayish brown or sepia brown, the base usually densely covered with long, coarse, flexuous, whitish fibrils, often far up the stipe.

Basidia 27-32 x 8-10 µm, clavate, 4-spored. Spores 8-12(-14.5) x 4.5-6(-6.5) µm, Q 1.3-2.2, qav 1,4-1.8, pip-shaped to almost cylindrical, smooth, amyloid. Cheilocystidia 30-65 x 5-18 µm, clavate, fusiform, lageniform or utriform, with yellow to colourless contents, with or without a neck or with one or more apical and/or lateral, simple to furcated or somewhat branched excrescences. Pleurocystidia absent. Lamellar trama dextrinoid. Hyphae of the pileipellis 1.5-5 µm wide, covered with simple to much branched excrescences 1-13.5 x 1-2 µm, forming dense masses. Hyphae of the cortical layer of the stipe 2-2.5 µm wide, smooth or covered with few to numerous simple to furcated excrescences, the terminal cells 2.5-10 µm wide, covered with rather coarse excrescences. Clamp connections present at all tissues.

Microphotos of cheilocystidia and stipitipellis

This is a highly variable species but the yellow shades at the pileus and stipe are good characters, as is also the usually distinctly coloured lamellar edge. Another typical feature is the stipe that often is covered with woolly fibrils far up the stipe. These "hairs" are visible in the microscope as long cylindrical cells up to at least 200 µm long. Some authours have accentuated the relationship to Mycena olivaceomarginata, and some have suggested that the two taxa belong to the same species. Maas Geesteranus (1988: 68), however, claimed that “in addition to their partly different ecological niches, M. citrinomarginata and M. olivaceomarginata may be told from one another in that the terminal cells of the hyphae of the cortical layer of the stipe in the former species are numerous, whereas these are absent in the latter or at least so rare as to appear absent”. In my opinion there is no doubt that the two taxa are representing two different species, and not only ecological forms, but the ITS sequences do not distinguish them.