[the_decider]

There is a simple 100% precision algorithm for detecting non-poisonous mushrooms in the continental United States. Look under the cap; if its spongy it won't kill you. It it's not spongy (aka ruffled), it could be poisonous so toss it out. Yes, your edible mushroom recall might be slightly reduced, but you're guaranteed to not get poisoned.

[HybridCurve]

This is exceedingly bad advice as there are several spongy mushrooms which are toxic in the US: Bolete Huronensis, Sutorius Eximius, Boletus Sensibilis to name a few. There are a few in genus Leccinum as well.

[vintermann]

You're - maybe - reasonably sure you won't die. You may still get really ill. North America isn't my area of knowledge, but I know there are several boletes that are poisonous, just not quite as deadly as the worst gilled mushrooms.

North America is also big, so these rules of thumb you have learned may not apply to a different part of it. I know that here in Norway, there's a rule that all mushrooms with true ribs (not sponge, not gills) - chanterelles -are edible. It's one of the easiest, most solid rules you learn here (from the state- approved official foraging society, something most other countries don't have).

But it's not true in North America. You have poisonous chanterelle varieties.

[londons_explore]

Works great till you find a little patch of mushrooms imported accidentally from Asia...