Historically shirts of this type would be linen or cotton homespun. Homespun fabric uses a nubby (less consistently spun) thread which produces a more textured fabric than a commercial loom might produce. This also produces a less consistent color as the dye is not absorbed equally by the varying fiber widths and lengths. Cotton fabric is normally softer but linen is more durable, breathable, wicks moisture better, dries faster and can produce a lighter weight fabric as the fibers are stronger and longer than cotton. It is the “performance” fabric of natural fibers. I would prefer a linen shirt over cotton in the high plains. Hope this helps.