The Master states (http://www.straightdope.com/classics/a3_024.html) that no-one knows how “yard” originated. OK, but it is interesting to note that standardization was thought sufficiently necessary that it was mentioned in Magna Carta (1297):
 One measure of Wine shall be through our Realm, and one measure of Ale, and one measure of Corn, that is to say, the Quarter of London; and one breadth of dyed Cloth, Russets, and Haberjects, that is to say, two Yards within the lists. And it shall be of Weights as it is of Measures.
cite: A translation of Magna Carta as confirmed by Edward I with his seal in 1297 (http://www.nara.gov/exhall/charters/magnacarta/magtrans.html)