Sally Archer was the wife of warp scientist Henry Archer, and the mother of Jonathan Archer.
When Jonathan had trouble sleeping as a child, Sally would often recite a poem for him. One poem she frequently recited was "The Song of the Wandering Aengus." (ENT: "Rogue Planet")
As Henry's Clarke's Disease progressed, one symptom was his inability to recognize his wife and son. After his death in 2124, she was forced to raise twelve-year-old Jonathan on her own. (ENT: "Cold Station 12", "In a Mirror, Darkly, Part II")
This character was only mentioned in dialogue.
Mike Sussman, who wrote "In a Mirror, Darkly, Part II", revealed that Sally Archer was named for the mother of Scott Bakula, who played Jonathan Archer.