William Salyers was out on a bike ride when he spotted these gigantic puffballs. Salyers said they were the largest he had ever seen. Most of them are about the size of golf balls, he said. Calvatia gigantea, commonly known as the giant puffball, is a mushroom commonly found in meadows, fields, and deciduous forests usually in late summer and autumn. It is found in temperate areas throughout the world.