Hi, I have a genealogy book of many of the descendents of Richard Ormesby (1602-1664) of Rehoboth MA. It was compiled by an Albert E. Pierce in the 1960s. He gave our family a copy of his last revised edition (1968) because he interviewed my grandparents several times.
Anyways, scanning through it last night I believe it makes mention of this Phoebe (it's spelled Phebe M. in the book). This Phebe M. was born in Beckett, MA on Feb 12, 1820. Her father was Elijah Ormsby Jr. (b. 1784) he was married to Susan Dewey. Apparently the family moved to Ohio because it notes that her father died "prob. in Lorain County, OH." She had six other siblings.
Unfortunately, the trail runs cold for Phebe after that. It does show that her older brother Elijah D. married in Loraine County and had a son Newton, and his family later moved to Decatur, Michigan