Any good Western supply store will carry silk neckerchiefs. These are usually 36 inches square or sometimes even bigger. They are really excellent light scarfs for your neck, potholders, slings, sweat dobbers, improvised hats, pressure bandages....you name it. I always have one in my vest pocket.

There is a website that has been linked here a number of times for a huge selection of colors and sizes. I cannot recall it right now though.

Winter Wise is a pretty good book.