You should not eat anything that you do not know for certain.
That applies to all plants and animals, not just mushrooms.

Knowing them includes whether it is edible and which parts and at what times of the year.
You know about shellfish, you might know about red tides and dangerous seasons for clams. You also need to know about local pollution sources and local algae blooms.

With fin fish you have the same thing. Some fish fresh from the sea can have toxic flesh or internal organs. We don't think of fish as being deadly poison but that is the truth concerning some of them.
Look up Fugu or Ciguatoxin poisoning for a couple eye openers about fin fish.

About the parts of the plants or animals I give two examples.
Potatoes are good food, but only the tubers are food and the rest of the plant is poison, and if the tubers turned green from being exposed to light they are as deadly as the leaves are. Seals are edible meat, but if you eat too much seal liver you get poisoned because they are too rich in Vitamin A.

Then there is the problem of how individuals react. Peanuts can kill people with allergies to them. Plenty of foods safe for me are deadly to some people.
There is even a lot of stuff on the supermarket shelf that can kill you.
So you should not eat anything you can't ID properly and know well.

To eat a wild mushroom without knowing what it is, well that is just begging for Darwin's Rules to be applied specifically to you.