Mycena sanguinolenta, commonly known as the bleeding bonnet, the smaller bleeding Mycena, or the terrestrial bleeding Mycena, is a species of mushroom in the family Mycenaceae. It is a common and widely distributed species, and has been found in North America, Australia, and Eurasia. The fungus produces reddish-brown to reddish-purple fruit bodies with conic to bell-shaped caps up to 1.5 cm (0.6 in) wide held by slender stipes up to 6 cm (2.4 in) high. When fresh, the fruit bodies will "bleed" a dark reddish-purple sap. The similar M. haematopus is larger and grows on decaying wood, usually in clumps. M. sanguinolenta contains alkaloid pigments that are unique to the species, may produce an antifungal compound, and is bioluminescent. The edibility of the mushroom has not been determined.