I also received this question from Herb Norman and have tried to help him find Oskar F. Nilsson, but with no result so far.
I have searched:
-birth records 1873 for Högby (Öland), Högby (Östergötland) and Högsby (Småland),
-list of removals (utflyttningslängd) 1893 for Högby (Öland), Böda (Öland), Källa (Öland), Högby (Östergötland) and Högsby (Småland)
but not found any matching person.
The information I have got from Herb is the following (from the Emigranten CD and family records):
Förnamn: Oskar
Efternamn: Nilsson/ Nelson Born 26 May 1873 believed to be in Kalmar Län.
Ålder: 20 år Kon: M
Församling: Högby Län: H
Utresehamn: Göteborg
Utvandrdag: 1893 09 15
Destination: Centerville
Källkod: 52:233:58472
He became a US Citizen on April 9, 1900 in Iron Mountain, Michigan. He returned to Sweden over a dozen times and married in Sweden in 1907. He brought his family of five to the US in 1918. They are only listed as leaving Amerika as they all were US Citizens by virtue of Marriage and Birth. I have spent about four hours going over the husförslängd for 1881-1894 and could not find him.
Herb is primarily looking for Oskar F. Nilsson's birth place in 1873 and wherefrom he emigrated in 1893. Maybe Sam Blixt, with access to the PLF database can help?