What exactly is "Mushroom Compost"?? Anyone know? thanks for your answers!

Anyone know?

thanks for your answers!

Answers: Button mushroom compost is traditionally straw and horse nourishment sterilized by Type I (traditional heat of decomp) and Type II (steam heated) composting. After the mushrooms own finished the "spent" compost is sold as garden suitable compost, free of most weed seeds. RScott