Demeaux Island
"[Iron & Misery] has a funger operation here, felling giant bolegus shrooms for building materials, harvesting kirralee for its 'medicinal' properties. It's a desperate little outpost of something like civilisation."

Demeaux Island is the location of the Iron and Misery Co. Funging Station, which is a huge mushroom-growing and -harvesting operation. Nearly all the workers here are slaves, who are of course eager to escape. Working conditions are poor, and escapees often complain that they need to pick fungal sproutlings out of their eyes. If one eats too much of the fungus grown here, the fungus will start growing inside of the victim, and then... never mind.
As the snippet above notes, the largest mushrooms harvested from the island's fungi forests are used as building materials. A smaller variety called kirralee is harvested for its supposedly medicinal properties.
(Editor's note: After a quick Google search, I determined that neither variety of mushroom mentioned actually exists IRL, though there is a type of mushroom called a boletus [not bolegus].)