Nilsen from Stavanger

I am starting to trace my mother Lillian Heffernan nee Simkins side of the family. Her Grand parents were Jacob and Marie Nilsen who immigrated from Stavanger Norway to Ames Iowa in 1882. I have no information on the history of the Nilsen family in Stavanger. Supposedly Jacob's Nilsens wife Marie's maiden name was Nilsen also. Any help with locating relatives or info would be appreciated My e mail is [email hidden] Fred Heffernan Rock Island Illinois