Coprinellus micaceus.

Mushroom omelette anyone?
A study of the mineral concentration of these mushrooms found high levels of potassium in fact close to half a gram of potassium per kilogram of mushroom. Unfortunately this particular species can accumulate detrimental heavy metals like lead and cadmium, it has been advised to restrict consumption of specimens collected from roadsides or other collection sites that may be exposed to or contain pollutants.