Could that Peter Ellingson be grandfather to Burtland Ellingson who 11.12.1938 married Ella Achterberg in Elbow Lake??
You could try to contakt Grant County Historical Society. in Elbow Lake.
P.O. Box 1002, Elbow Lake, MN 56531
They were very helpfull to me. Patty Benson was my very good helper.