Cocoa shells from a Hershey’s chocolate plant in Hershey, Pa., are just one ingredient in the compost that mushroom growers use to feed the fungi.

Cocoa shells from a Hershey's chocolate plant in Hershey, Pa., are just one ingredient in the compost that mushroom growers use to feed the fungi.

Cocoa shells from a Hershey’s chocolate plant in Hershey, Pa., are just one ingredient in the compost that mushroom growers use to feed the fungi.

Cocoa shells from a Hershey’s chocolate plant in Hershey, Pa., are just one ingredient in the compost that mushroom growers use to feed the fungi.