Red/Brown color on some Shiitake Mushrooms These mushrooms have been in the fridge for two weeks (sealed by wrap)

Are they bad already? what cause the red/brown color(only under it, not on top)?

Thank you.
Already? They were probably bad last week :-). I know mushrooms often come wrapped in plastic at the store, but they'll last much longer if you take them out of the plastic. If they're discolored (and probably soft), don't eat them.