A key identifying feature for many mushrooms is whether they “bruise” or “stain” a certain color. To test this you don’t have to punch your mushroom, or drop it off a small cliff. Simply scratch the surface with a knife, or if you don’t have one, your fingernail, as above.
It can also be useful to slice through the mushroom to see if the “flesh” (ie. the part that is not pore surface or gills) stains on exposure. Some mushrooms stain immediately, others stain slowly. Consider these time lapse photos of a black-staining russula:
Some of the most famous examples of bruising mushrooms are Artist’s Conk (so-called because people more talented than me can draw cool pictures on the bruising undersurface), Psilocybe (“magic”) mushrooms, and the Indigo Milk Cap, which stains first a brilliant blue and then slowly turns a sea-green.
recycled paper clips 