Possibly Glistening Ink-cap (Coprinus micaceus)

Mushrooms like rich soil, and somewhat damp soil. I am currently growing them in a big cardboard box from a kit. Since January I have been harvesting mushrooms about once a week. Once they get over the size of a dime in diameter, it takes only a day or two longer for them to reach 2 inches in diameter. Mine are a common white mushroom, but the jumbo size for stuffing. Right now, the yield has greatly deminished and I just get may one or two per week. Soon the whole setup will ge dumped into my compost pile, as its mostly exhausted. Mushrooms are usually a healthy thing, but it may also be from a bit too much moisture in the soil for them to sprout from a green growing plant medium.