I looked in the most likely place for finding a Washburn-Hayward pairing, which is Bridgewater, MA. Her husband was indeed Solomon Hayward, not Howard (which was given by P.R.1. for the marriage record) - in Bridgewater, the Howard/Haward family is sometimes confused with the Hayward family, although they are two different families.
WASHBURN ... Zerviah, ch. Jonathan and Rebecca, Apr. 9, 1760. [Zeruiah, w. Solomon Hayward, P.R.1.] [Bridgewater VR 1:337] P.R.1. - private record, from a record kept by the Rev. Richard M. Hodges, now in the possession of the South Parish Church
Dale H. Cook, Member, NEHGS and MA Society of Mayflower Descendants; Plymouth Co. MA Coordinator for the USGenWeb Project Administrator of http://plymouthcolony.nethttp://plymouthcolony.net