We took a wide strip of cloth and wrapped it around our cabbage merchant's head until it looked right... Yeah, we cheated.
For fabrics, I used a linen from Jo-ann's and it looked wonderful. It's got a texture that I feel really works for Earth Kingdom, and it's ridiculously easy to dye with RIT (or your personal favorite, but RIT is easiest to get for most) if you can't find the colors you need. It's more expensive than the broadcloth cottons that a lot of people go for, but you can use coupons and the look and drape is just so much nicer. Also, they have a lot of linen/rayon blends that are cheaper, but look about the same.