The Stafford knot, sometimes incorrectly referred to as the Staffordshire knot, is a distinctive three-looped knot that is the traditional symbol of the English county of Staffordshire and of its county town, Stafford. It is a particular representation of the simple overhand knot, the most basic knot of all.

The knot was the badge of the de Stafford family, who were first found in the Domesday survey.
 

Additional information:

http://news.bbc.co.uk/local/stoke/hi/people_and_places/history/newsid_8401000/8401651.stm