Hygrocybe conica (Zwartwordende wasplaat (BE) / Witch's hat (EN) / Schwärzende Saftling (DE) / hygrophore conique (FR)) is is a colourful fungus of the genus Hygrocybe (the waxcaps) in the Hygrophoraceae family.
Other members of this genus in my older posts can be found here)

This member of the waxy cap group is recognized by its distinctly conic cap (sometimes convex with a conic point), usually between 2 and 7 cm. Fruiting bodys are colored yellow to scarlet when young, but all parts of the fungus blacken in age or when bruised. Occasionally one will encounter all black, still relatively fresh specimens (like the one in the image) in the field.
Most specimens I found had only irregular spots or parts blackening but in this one the almost complete and very even half-way blackening of the yellow cap resulted in an almost bronzen or golden colored specimen, accentuating the typical finely hairy structures in the cap. By far the most beautiful specimen of this species I ever saw !

Image: Schilde (BE) - 05/10/2010