Aunt Bea
Master Chef
My grandmother (the one who was a great cake maker but a bad cook with anything else, used to soak mushrooms in salt water for a minimum of half an hour "to make sure they weren't poisonous" (don't ask!). By the time they came out of the water they were soggy and waterlogged and they stewed rather than fried so you never got a lovely fried mushroom with a firm texture and nice browned edges.
We used to soak wild field mushrooms in salted water for a few minutes. My Grandmother thought that it would force out any bugs or worms that might have infested them, not sure if it was true or not.