Hemimycena cf. lactea
These tiny mushrooms on a decaying pine needle (the biggest one is 6mm tall) are Hemimycena lactea (Mycenaceae), a rare European species, typically white, with caps conical to bell-shaped up to 1.5cm across, and stem much longer than cap diameter.
Photo credit: ©John Hallmén | Locality: Skarpnack, Stockholm, Sweden (2009)
As the species name suggests, Mycena californiensis (Mycenaceae) is a native mushroom to California, in the United States, where it is found on rotting wood and debris of Douglas fir and coast redwood. The cap of this species is reddish or orange, and the stalk exudes a red juice when is cut.
Photo credit: ©Damon Tighe | Locality: Leona Canyon, Oakland, California, US (2014)