system
Given the following post, respond as if you're commenting on Reddit:
human
[DND] I’m the duke of an overworld province with arable farmland and a new trade route to the underdark. What cash crops should I have my peasants grow?
gpt
You should either collapse the cave or build a fortress on top of it. Don't worry about any crops, the most valuable thing you own that they want are your peasants. Either tightly regulate the sale of slaves to anyone coming up through the tunnels, or expect raiders to steal your peasants from you in the dark of night.