I don't see why this could possibly get downvoted, it's absolutely true. If you do have a "hard and fast" rule in mind, it may work in your region but not in other places.
> If you do have a "hard and fast" rule in mind, it may work in your region but not in other places.
There are lots of hard and fast rules in different regions though that do work if you can ID the mushroom to genus. E.g. in New England, no green mushrooms in the Russula genus are poisonous.
