Bernhard Peterson, abt 1853, and Olivia, abt 1865

Barney Peterson, b Norway, abt 1853, spouse Oliva, b Norway, abt 1865, appear in the Wisconsin State Census, 1895 /1905 on-line dbs on Ancestery.com, residence on 1 Jun 1905 - Grant, Dunn, Wisconsin, USA. As you move forward, or back in time, thru census records, it appears that census takers had difficulty with his name. I did further lookups on his son, Andreas, b abt 1902-3. In the 1920 Federal US Census, Bernhard's immigration date is given as 1875. He still is in Grant, Dunn, Wisconsin, USA, listed as Bernhard Peterson and his wife's (Olivia) immigration date is listed as1875. I am requesting assistance to determine where they originated from in Norway on behalf of their grand daughter, Ellen, who is now in her 80s. These two kindly folks, Barney and Olivia, carried for my grandpas very elderly grandparents (John Jensen Grundseth and Anna Gurine Olsdtr) until their deaths. The children of the Grundseths had all died, by the time they reached their early twenties. Any assistance would be appreciated.