The Enid Blyton Society

Hmm. That does seem to be a folk song, some hunting online reveals that it was first collected in 1955. Since the song refers to "ketchup" I thought it couldn't be very old, but I just checked the OED which first records the use of the word ketchup in English from 1699. And according to the OED ketchup or catchup or catsup originally could indeed be made of mushrooms or walnuts instead of tomatoes, nowadays I think ketchup is always made from tomatoes. The word seems to come from Chinese.

Living in the relative safety of Britain as far as nature goes, I've always thought of toadstools as rather terrifying! Mushrooms (which I don't particularly like anyway) are cultivated for food, and yet toadstools can kill you.