At least in the U.S. and Canada, there are no mushrooms where if a healthy adult nibbles on them to taste them and then spits them out, they will be anywhere close to the LD50. You might still get some minor liver damage or whatever, but not enough to kill you. This is as opposed to plants, where people have died just from putting water hemlock twigs in their mouths to play with.

There are a bunch of similar-looking species where the proper way to ID them to know if they're edible or not is actually to nibble on them and then just spit them out.