Thanks to the comrade /u/nohaybanda , who told me I should go out anyway even if i did not find anything. Was fun and relaxing. Met some nice old ladies who were much better at foraging than I am.
I am going to put the parasol in a panade and fry them in fat.
Hmm, I would think it's not because of over-harvest (since most mushrooms have enormous myceliums that expand asexually), but because mushrooms have very specific fruiting conditions. Like, the parasol fungus are rocking all year living in the earth, but only sprout when humid/rainy and cold-without-freeze for a few days. So I blame climate change :agony-deep: