Originally thought that this might be G. frondosa. But not dark enough, and fruiting bodies are much smaller than Grifola genus. Found in leaf litter a week after the last rain.
Instantly staining dark blue, fading to brown. Stains fingers too. Near oaks. Cross-section deep blue throughout when cut. Pileus brown, almost black w/ KOH. Context orange-brown w/ KOH on both cap and stem.
Dead tree (unidentifiable but probably maple) in sandy soil
Subtle staining if any (see third picture). Faint orangish KOH reaction on cap.