Mushroom

Mushrooms are a type of fungus that reproduce by means of spores.

Mushrooms were common on the planet Krypton, prior to her destruction, when Krypton was a lush world. When the planet finally exploded, certain mushroom spores shot out into space, and some hitched a ride on a chunk of Kryptonite. This chunk of Kryptonite is later found by Paw Martingale, when it crashes into his pea patch. The spores survive the trip, and reproduce, causing mushrooms to grow everywhere on his land.