Another common name for Mycena Haematopus is Bleeding Mycena, but if you can call a mushroom Bleeding Fairy Helmet, then I think you should. The color of this mushroom is somewhat variable, usually a brown and purple hue, quite lovely. The cap is conical, convex, and sometimes a bit umbonate. It's somewhat striate. The gills are much paler than the cap and are narrowly attached to the stem. The largest specimen I collected had a stem 7 cm long and nearly 3 mm wide. The cap was 2 cm across.
Two key diagnostic features: growth on well-decayed wood and the purple-red juice. Just carry some about for a while, and if your hands stain, you know you got the Bleeding Fairy Helmet.
The spores measured 8-10 μm.