Put the scraps from the mushroom cleaning in a pan with cold water and cook.
Boil the stock for approximately 30 minutes over a low heat.
Turn off the heat and let the mushroom soil settle on the bottom of the pan.
Filter the stock through a fine mesh strainer, on which you will also have to put some gauze to increase filtration.
You can use mushroom stock to enhance the taste of mushroom soup or other mushroom based dishes.