a blighted mushroom

This small mushroom's cap is mostly a healthy, luscious golden-brown hue, but the image of health is dispelled by mottled patches of grey and green. A dark fluid seems to seep from the blight, discolouring the rim and the gills on the underside.

It is a blighted mushroom.
It weighs a couple of ounces.

You identify a blighted mushroom.
It is contaminated food.
It weighs two ounces, and it is worth about one celeb.
Its keywords are mushroom, inkcap, blighted, and blotchy.