Mushrooms

Everyone is familiar with this weird characteristic of mushrooms: they spring out of the ground ove
ight, fully grown, whenever they get a good rain and enough warmth to trigger their development. You go to sleep with a lawn and wake up to a mushroom hatchery.
The good news is that mushrooms need decaying organic matter, which is rich in nutrients, in order to grow, and if they sprout on your lawn that means your soil is very healthy. They don’t need sunlight or dirt, they’ll grow anywhere: dark basements, rotting wooden logs, they’ll even sprout sideways on the trunks of old trees. Some mushroom types, truffles, for instance, don’t bother to break out of the ground at all and live their happy stealth lives completely buried.
That’s where the largest part of the mushroom lives anyway, underground, where it forms an intricate network of filaments which span for miles and survive for thousands of years as long as there is sufficient decaying matter to feast on.
How do they grow so fast? My understanding is that the cells of their fruiting bodies divide and get fully formed beneath the surface of the soil, where the mycellium can accumulate large quantities of nutrients over time, and when moisture becomes available, the cells simply swell up with water and make the caps pop out of the ground. A mushroom is over 90% water.