Phylloscypha phyllogena

Scientific name:  Phylloscypha phyllogena (Cooke)
Van Vooren
Derivation of name: Phyllo means "leaf" and scypha
means "cup."
Synonyms:  Peziza phyllogena Cooke; Peziza
badioconfusa Korf
Common name(s):  Common brown cup
Phylum:   Ascomycota
Order:   Pezizales
Family:   Pezizaceae
Occurrence on wood substrate:  Saprobic; solitary
or clustered on well-decayed wood (especially
moss-covered stumps) or on the ground; spring
through early summer.  
Dimensions:  Up to 15 cm wide; deep to shallowly
cup-shaped, flattening with age; stalkless.   
Sterile outer surface:  Reddish-brown; dull,
scurfy.       
Fertile inner surface:   Reddish-brown to
olive-brown; smooth.
Comments: Although this fungus resembles Peziza
badia, P. badia fruits in the fall. The two species also
differ in spore morphology. See the following website
for further cautions in identifying P. phyllogena.

More information at MushroomExpert.com:

Figure 1. Typical specimen of Phylloscypha
phyllogena. The cups become quite irregular in
shape when growing in clusters.
Photo © William Roody