Megacollybia platyphylla

Scientific name:  Megacollybia platyphylla (Persoon:Fries) Kotlaba and Pouzar
Derivation of name: Platy- means "broad" or "wide" and
phyll- means "leaf" or "leaves" referring to the gills.
Platyphylla means "broad-gilled."
Synonyms:  Tricholomopsis platyphylla (Pers.) Singer;
Collybia platyphylla Fr.
Common name(s):  Broad gill; Platterful mushroom.
Phylum:   Basidiomycota
Order:   Agaricales
Family:   Tricholomataceae
Occurrence on wood substrate:  Saprobic; solitary to
several on and near deciduous logs, stumps, wood debris or
on ground from buried wood; May through October.  
Dimensions:  Caps 5-12.5 cm wide and stipes 7.5-12.5
cm long and 1-2 cm thick.  
Cap:  Smooth; brownish-gray caps; radially streaked with
dark fibers.      
Gills: Attached; white; broad; edges uneven to ragged,
appearing eroded.
Spore print:White.
Stipe:White, smooth, with white rhizomorphs present at the
base.
Veil: Absent.
Edibility: Edible.
Comments: One of the first large mushrooms to appear in
the spring.

More information at MushroomExpert.com:   


Figure 1. A group of platterful mushrooms arising from a
stump. Photo © William Roody.
    

Figure 2. This young specimen is oozing water from the
stipe. The gill edges are even. A white rhizomorph is visible
to the left of the stalk base. Photo © Gary Emberger.

Figure 3. Megacollybia platyphylla. Photo © John
Plischke III.

Figure 4. Caps sometimes crack or split when drying out.
Photo © Gary Emberger.

Figure 5. Caps of Megacollybia platyphylla are streaked
with dark, radial fibers. Photo © Gary Emberger.

Figure 6. The gill edges of this mature specimen are quite
ragged. Compare to the gills visible in Figure 2.
Photo © Gary Emberger.