Why do mushrooms appear after rain?
The short answer
A mushroom is a fungal fruiting body for spreading spores, and moist conditions often trigger it to appear above the ground.
How it works
The main body of many fungi is a network of fine threads hidden in soil or wood. When moisture and temperature are suitable, it can quickly produce a mushroom that releases spores.
A familiar example
Whether a mushroom is safe to eat cannot be decided from its appearance alone.