Clathrus columnatus, commonly known as the columnar stinkhorn, is a saprobic species of basidiomycete fungus in the family Phallaceae. It has a widespread distribution, and has been found in Africa, Australasia, and the Americas. It may have been introduced to North America with exotic plants. Similar to other stinkhorn fungi, the fruiting body, known as the receptaculum, starts out as a subterranean "egg" form.
Columnar Stinkhorn Mushroom

Rebekah D. Wallace, University of Georgia, Bugwood.org