, also known as elm brain or brown witch's butter. I had fungi on my own brain because earlier I had done a zookeeper training class on mushrooms.
One of the students spotted this group of attractive agarics! I plucked one, bisected it to show that the gills were free (not connected to the stalk) and brought half of it back to take a spore print.
The spores were dark brown. This, along with the habitat (growing directly on the ground), the prominent ring, the free pinkish gills, the tan and white cap, and the thick stem all added up to the genus Agaricus
, the same group that grocery store buttons and portobellos belong to. However a combination of other characteristics including the scaly top darkest in the middle, the fact that the flesh bruised reddish when handled, and tand geography (northeastern US) leaned it toward A. placomyces
, a species known to be poisonous, at least to some people. In the future I'll know to look for a phenolic smell and bright yellow color inside the base of the stem to positively identify mushrooms to this species.