"Head Coverings of Medieval English Noblewomen", by Seduced By History
... "Women almost always wore headdresses because it was considered unseemly for them to show their hair. In William the Conqueror’s time, women simply wore a piece of plain cloth (often linen) draped over their heads, held by a narrow band. Some women wore their hair in two long braids around the turn of the 12th century, some with no veils. By Stephen’s reign, headbands were coming into vogue. These were worn with a veil."