From Discworld MUD Wiki
Cabbages are, well, cabbages. It is a leafy green vegetable, and one of the major Discworld crops, especially on the Sto Plains
This is a cabbage. Cabbage is the oldest and most widely grown vegetable of the brassica group, belonging to the mustard family.
Note that if you eat cabbages, gas (for a short time) will result.
Cabbages can be found in the following locations: