Spritz with water: If the mushrooms appear very dirty, place them in a colander and spray them with water until the dirt washes away.
Clean: Using a damp cloth or paper towel, gently wipe each mushroom until it is clean.
Remove stem: Gently snap off the stem from the mushrooms pulling sideways, leaving the mushroom cap hollow.
Notes
Avoid rinsing: The mushrooms will become water-logged and soggy if washed under running water.
Use as soon as you can: Once cleaned, its best to use the mushrooms right away to avoid spoilage.
Do not store in plastic: That being said, mushrooms will keep for 2-3 days in the fridge when stored properly in a brown paper bag or the crisper drawer.
Note: The nutrition facts below are my estimates. If you are following any diet plan, I recommend cross-checking with your preferred nutrition calculator.