Green-Spored Parasol, Green Gill
Highly poisonous and producing severe gastrointestinal symptoms of vomiting and diarrhea,is the most commonly consumed poisonous mushroom in North America. The nature of the poisoning is predominantly gastrointestinal,and can be so severe as to be fatal.
This time of year, they are springing up everywhere and can get quite large. I have read that one reason for some poisonings is that Asian immigrants are used to eating a mushroom that looks like this in the Asian Indonesian countries they come from, so make the assumption this look-alike is good to eat.
I have been watching the squirrels eat this mushroom quite avidly.