GOODMANSON-GUNDERSON

I am looking for information on Burdines GOODMANSON(I'm pretty sure that wasn't the way it was always spelled) and Ellen Julia GUNDERSON. She was born Feb 1863. They were both born in Koppervik. They immigrated to the US in 1885. Stayed with friends in LaSalle County, Illinois for 4 years then moved to Benton County, Iowa. He died in Benton County in 1900. Any help would be appreciated as I have hit a brick wall with the GOODMANSON surname!!