Amund Olson

You all were so helpful in assisting me with researching my history before, I was able to get back 38 generations on my paternal grandmothers mothers side, but now I am stuck with my paternal grandfathers side. The farthest I can get back is to Amund Olson (b. 1832) and Mary Olson (b 1842). I know they were born in Norway and when they came ot the US based on the US census data I was able to find. I can't find Mary's birth last name. I believe when they came to the US and settled in MN or ND. They had one son, Ole Amundson in 1866 in Norway, prior to coming to the US. They had Oscar, Bertha, Caroline, Mary, Johane, Gladys, Amund, Fredrik, Gurina, Johannes, Anna and Anton after arriving in the US. I have been searching and searching but I can't find any more records on Amund or his wife Mary prior to coming to the US, or any records of Mary or Anton's death in the US. I am interested in their parents names, Mary's birth name and their DOD. Any other information would be helpful as well. Can anyone help with this one? Thank You!!