Maybe even 100%, depending on the mushroom.
That was my first thought.
The 2 gentlemen who *taught* it had combined experience of 69 yrs.
Basically we foraged in the woods....came back to the starting point picnic table w/ our finds. The UCONN instructors went thru all the mushroom names, etc.
They even found 2 they couldn't identify. They discarded 99.9% of them. It cost me $45. to learn not much of anything....[like most college courses]
Then they cooked up the edible ones on a little camp stove. We ate the samples.....some people didn't [chortle]
My only takeaway....don't eat ANY mushrooms you find in the forest....chances are, you will get sick. I didn't learn enough, to make me feel confident in the hobby. :)