ID PLEASE and thank you!

[Lee]

End of April mid Atlantic found on mixed shredded wood chips in old horse pasture 60- 70degree days 40 50ish degree nights dark spore print

[Dave W]

Almost certainly a species of either Agrocybe or Cyclocybe. (Cyclocybe is a "split-off" genus from genus Agrocybe.) Given the habitat and time of year, I'd say Agrocybe is more likely. The name "Agrocybe praecox" is typically applied to springtime Agrocybe mushrooms that grow on wood chips. There are probably a few distinct species within the Agrocybe praecox species group https://www.mushroomexpert.com/agrocybe_praecox.html. There's also a few Agrocybe species that have their own names, like Agrocybe dura or A. paludosa, that may occur during springtime. All Agrocybe and Cyclocybe mushrooms have cigar-brown spore prints, like the print seen here.

Kuehneromyces marginellus is another brown-spored mushroom that occurs during spring. It usually produces smaller mushrooms than Agrocybe praecox, and tends to grow in forests more often than on mulch/wood chips. But I have found this common species on wood chips or piles of woody debris. Kuehneromyces marginellus can look a lot like an Agrocybe species. Sometimes, to tell the difference one needs microscopic analysis. 

Another brown-spored wood-inhabiting mushroom that is often found in spring is the deadly poisonous Galerina marginata. This species most often grows in the forest on old downed logs or stumps. But I have infrequently seen it growing form buried wood. Mushrooms of G. marginata are generally smaller than Agrocybe praecox, and the spore print of G. marginata tends to have a rusty hue. Microscopically, the spores are quite different from Agrocybe. 

[Lee]

Thanks Steve appreciate the info