Lichen Agaric

I discovered about six of these tiny mushrooms growing on a rotten stump on 14 April 2020. They were along a trail near Lake Quinault, Washington. Without hesitation, iNaturalist identified them as Lichen Agaric, Lichenomphalia umbellifera. These mushrooms harbor symbiotic, single-celled green algae, Coccomyxa. Presumably the algae provide some nutrients to the mushrooms, which, in turn, give the algae somewhere to live. Oddly, the mushroom spores do not contain algae, so that the algae must be able to disperse on their own.