When I was a kid, we used to sing the following (it's more like a chant):
Mushrooms are a vege-table
That you eat when you are able
You will know them when you see them
You will know them when you eat them
If in heaven you awaken
You will know you were mistaken
And the ones that you had eaten
Weren't the ones you thought you ate!!!
(Must've been a toadstool -- tough luck!)
Hope you like! :D