The descendants of David Yaw or Yaugh and his wife Jane has been traced from various records, including baptisms and burials of their children in Marblehead, Massachusetts and Scituate, Rhode Island in the early 18th century. For the family of their son Joseph Yeaw see Joseph Yeaw and Martha Thornton.
It seems very likely that David Yaw was an emigrant from Somerset, but the link has not been traced with any certainty.
For more information see the 1962 book The Yaw-Yeaw Family in America published by the Yaw-Yeaw Family Society and its 1970 supplement.