Earthcaller Ryga at Mag'har Post in Hellfire Peninsula wants you to bring her 1 Drycap Mushroom from a cave inside the Great Fissure.
It is good that you've offered to aid us, [player]. Our grunts have fallen sick from drinking contaminated water and I'm missing an ingredient to produce a healing salve. I'm in need of a rare mushroom called drycap.
Our foremost orders are to keep our location secret and not risk being spotted while looking for it, or I would go myself. The only place in Hellfire Peninsula where drycap grows is a cave at the Great Fissure, south of here.
Be extremely careful if you choose to seek it.