Even store-bought mushrooms should be cooked. There is some evidence that the common white button mushroom contains some carcinogens when raw.

https://grantome.com/grant/NIH/R01-CA031611-05

(Note: other studies have concluded the dosage is too low for concern, the jury is still out)

But also, many kinds of bacteria can thrive in mushroom growing conditions - good idea to sterilize before you eat.