Huge, white, smooth ball; completely white interior becomes yellowish green with age. Grows in open pastures, woods, and lawns. May–October. Fruiting body round; outside white; inside pure white when fresh and young, yellowish green with age; outside texture smooth, soft, cracking irregularly; inside texture marshmallow-like; there is a rootlike attachment at the base. Spore print greenish brown. Spores magnified are round. A giant puffball can be very large — as big as a soccer ball or even much larger.
Lookalikes: Some other types of white mushrooms, including the deadly destroying angel (Amanita bisporigera), have stages in which they could be mistaken for a puffball. Make sure you cut through any puffball from top to bottom to confirm that it is pure white inside, like a marshmallow, with no sign of a cap or stem.