Hi! I think this is a butter cap (Rhodocollybia butyracea). The cap looks greasy, as if rubbed with butter, and it’s dark when wet, then turns paler from the edge as it dries, just like on yours. But the second photo shows the main thing: the gills are white and crowded, and the stem gets thicker towards the base and is covered in white fluff with needles stuck to it. It’s conditionally edible: people take only the caps and always boil them first, and the taste is nothing special. It has a lookalike, the lilac bonnet (Mycena pura), and that one is poisonous. The bonnet smells strongly of radish when you break it, and its stem is straight and even. So I wouldn’t eat it based on photos alone. Small brown mushrooms are easy to mix up, so if you’re in doubt, leave it 🙂