Peter Guttormsen (Ode) of Decorah

I am looking for information on Peter Guttormson who settled in Decorah, Iowa. In America he went by Guttormson and his children went by the last name of Ode. He had six sons and three daughters. (Peter was buried under the name Ode, also.) He was born in Norway in 1834 but I don't know where. Does anyone have information on this family's origin? Thanks!