Psathyrella delineata
Found May 20th after several days of rain.  Growing from
well-rotted wood.  Note corrugated cap, hollow stem,
attached gills and white partial-veil remnants on cap margin.
Complete description at
DNA work:
"Psathyrella of Indiana. 29 species across 152 sequenced collections.
The working list can be found below. We do need more spring
Psathyrella collections. They are underrepresented in this list.
Particularly things you may call P. pseudovernalis (P. umbrosa) or P.
Psathyrella agrariella 4
Psathyrella albescens 4
Psathyrella amarescens 8
Psathyrella bipellis 3
Psathyrella candolleana 35
Psathyrella delineata 11
Psathyrella ephemera 1
Psathyrella friesii 2
Psathyrella impexa 1
Psathyrella kauffmanii (P. phegophila) 12
Psathyrella multipedata 1
Psathyrella orbitarum 1
Psathyrella piluliformis 4
Psathyrella psammophila 9
Psathyrella septentrionalis 5
Psathyrella spadiceogrisea 1
Psathyrella spintrigeroides 3
Psathyrella sulcatotuberculosa 1
Psathyrella umbrosa 1
Psathyrella "sp-IN01" 10
Psathyrella "sp-IN02" 3
Psathyrella "sp-IN03" 2
Psathyrella "sp-IN05" 3
Psathyrella "sp-IN06" 2
Psathyrella "sp-IN07" 3
Psathyrella "sp-IN08" 1
Psathyrella "sp-IN09" 1
Other species I have called Psathyrella in the field:
Coprinopsis "sp-IN02" 6
Parasola conopilea 2"
Steve Russell, Purdue. April 2020;
from "Indiana Mushrooms" Facebook group.