This cache is not at the posted coordinates. You have to solve an easy puzzle first. 

Heads up: Sugar sand is tough terrain to walk on. Bring lots of water. 

Rusty Gilled Polypore - Gloeophyllum sepiarium 

a wood decay fungus that causes brown rot. It has orange to reddish brown or nearly black (as it ages) dorsal surface, usually with distinct bands, although becoming more uniform with age.

It is not poisonous but also not very tasty because of the tough, corky texture. Similar to other fungus, it is believed to have antioxidant and anti-cancer properties. 

Cache placed with permission from the Seabranch preserve park manager Christopher Camargo.