Mushroom the Journal's Key to the Gilled Mushrooms in The Audubon Society Field Guide to North American Mushrooms
by Gary Lincoff
first published in the Summer 1985 issue of Mushroom, the Journal of Wild Mushrooming
The key starts with the spore color of the mushroom:
Spores White to Cream or Yellow
Spores Pink to Salmon, Brownish-Pink, or Reddish
Spores Ochre to Rust or Chocolate Brown
Spores Purple-Brown to Purple-Black, Smoky Black or Black
Mushroom, the journal for all seasons