Looking for Flyum relatives

I am trying to figure out when and on what ship Lars and Kari Flyum came to America on. I have found them in several different census records. In the 1895 MN state census Lars is listed as a resident of the state for 24 years. and the enumeration district of Brandon, Douglas County for 12 years. In the 1900 census Lars is listed as imigrating in 1872 and Kari is listed as immigrating in 1868. In the 1910 census Lars is listed as immigrating in 1871 and Kari is listed as immigarting in 1865. Kari's maiden name was Melaas and she was born in 1840. So, what I would like to start with is finding when they came to America and on what ship and where they came to. Kari may have gone to relatives in Ulen, MN, but I'm not sure. I can't seem to find Lars and Kari in the 1880 US census. I believe they were married in 1875 Any help would be appreciated!