Anie (Annie) Severson
Birthdate and birthplace :
Annie – 1898 / Wisconsin (town unknown)

Parents (include names, dates, and places) UNKNOWN
Siblings (include names, dates, and places)
Sever (or possibly Siver) Severson
29 Dec 1893 / Wisconsin
Annie's spouse(s) Mike Johnson (other data unknown)
Children (names, dates and places)
Harry Severson / 1914 / Wisconsin
Olaf Carl Severson / 14 Oct. 1918 / Arland, Barron Co., WI
Emigration Date UNKNOWN – from Norway
Emigrated to Wisconsin
Specific location(s) where person lived:
Arland, Barron Co., Wisconsin

Everything else I know about the person or family:
In the 1920 Federal Census of Barron County her age is given as 22, but in my father's (Olaf Carl) in 1918 it is also listed as 22.
Her brother Sever's birthday is 29 Dec. 1893. In the Censuses they are listed as being born in Wisconsin, but no city is given. Their parents are listed as coming from Norway, but I can find no names or dates of immigration for them.
The resources I have already searched (be specific)
World War I Draft Registration Card for Sever H. Severson, filled out in 1917, living in Dane Co., Wisconsin.
In 1920 Barrron Census, Sever is listed as "Head" for Annie, Harry and Olaf, but there is a Sophia Lammert and her son Otto (age 29) directly in the lines above.
Later in WW2 Olaf wrote on a photo of one of Otto's sons "my half-brother."
In the 1930 Barrron Census they are listed under Sion Severson as "nephews".
What I would like to find out :
The names of the PARENTS of Annie and Sever Severson, and when they immigrated to the U.S
Also: which port did they depart from when leaving Norway and which was their arrival port in the U.S.