T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Leucocoprinus birnbaumii (Flowerpot parasol)

Kingdom: Fungi
Division: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Agaricaceae
Genus: Leucocoprinus
Species: L. birnbaumii
Binomial name: Leucocoprinus birnbaumii
Synonyms: Lepiota lutea, Leucocoprinus luteus, Leucocoprinus flos-sulfuris, Lepiota cepaestipes var. luteus.
Common names: Flowerpot parasol, Plantpot dapperling, Yellow parasol, Yellow houseplant mushroom, Lemon-yellow lepiota", Yellow pleated parasol.

Leucocoprinus birnbaumii is a little saprobic yellow mushroom that pops up in flower pots alone or in clusters. It also appears in warm conditions in greenhouses, gardens and the edges of paths.
The fruit bodies are mushroom-shaped. All parts are bright, pale sulphur-yellow that fades with age. When young, the cap is usually oval, later becoming broadly conical or bell-shaped around 2.5-6 cm across. The bright to pale yellow cap is often darker at the centre. The caps surface is smooth but dotted with fine, easily detached scales. It often develops shallow, grooves that radiate from the margin nearly to the centre. 
The gills are free (not attached to the stem) and are covered by a partial veil when young, which ruptures to leave a fragile, evanescent ring on the stem.

Photos of developing mushrooms below.


Remnants of an evanescent ring on the stem.

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/