Green-spored Lepiota - Chlorophyllum molybdites
A pictorial tour of some of this poisonous mushroom's features.
Described as fruiting in August through October, but it matches the description given in Mushrooms of Northeastern North American very well. A noteworthy feature (noteworthy only because this is such a nondescript mushroom) is the collar at the top of the stem where the gills attach (not pictured).
Laughing Gym - Gymnopilues junonius
This patch of mushrooms has grown to be quite large since this picture was taken. The darker orange mushrooms in the background are older ones.