Flour

Ground grain, mainly wheat, rye and barley, often in mixtures such as maslin. Domesday Book records over 6,000 mills in 1086, most of them watermills; windmills are first recorded in England in the 1180s. Lords commonly required tenants to grind at the manor mill and pay a toll, though hand querns remained in use. Finer, whiter wheat flour was the more prized.

Sources: millsarchive.org · medievalists.net