Take the buttons or slaps, clean them and set them in an earthen dish or dripping pan one by one, let them stand in a slow oven to dry whilst they will beat to powder, and when they are powdered sift them through a sieve; take the mace, and nutmeg, beat them very fine, and mix them with your mushroom powder, then put it into a bottle, and it will be fit for use.
You must not wash your mushrooms.