I am a descendant of some Thayers. My Thayer ancestor is a Comfort Thayer, daughter of Isaac and Mercy Thayer of Mendon, MA. Comfort was from Mendon, and in 1722, she married James Keith (of the Rev. James Keith's line from Bridgewater.) They removed to Uxbridge in 1726. She died there, on 22 Aug 1775, aged 75. So she must have been born in 1700 or thereabouts. Don't know if this will be of help to you. I could do some more digging for you, through my info. Get yourself a copy of "The Vital Records of Mendon, MA to the Year 1850" and see where that leads you. You could probobly find it in your local research library in the genealogy section. Or if you are living in the area, I know the Worcester Public Library must have a copy. Best of luck in your research. - Joel B. Keith.