I found a Declaration of Intention from 1914 in the District of Vermont for a Fred Johnson born on 25 January 1890 in “Gevar”, Germany. This is probably referring to Jever, as Dieter suggested, and is north of Oldenburg.
It says he immigrated from Bremen, Germany and landed in Ellis Island in July 1909. He was living in Bellows Halls, Vermont. He signed his name “Fred Jahnson”.
I also found a Veteran Cemetery Record from Maine for a Fred Johnson born in 1890 in Germany. Like the Declaration of Intention above, Fred is listed as a cook. His address was Waterville, Maine. He died on 25 September 1939 in Torrington, Connecticut due to coronary occlusion and was buried 3 days later in Pine Grove Cemetery.
I found that marriage record you were talking about from 12 February 1918. His parents are listed as Diedrich Johnson and Emma Crow, both from Germany. His mother’s maiden name was probably Kroh or Krahe, since those are the German forms. He worked as a baker’s cook in Bellows Falls, Vermont.
He lived in a home for disabled veterans in Togus, Maine from 16 September 1932 until 18 November 1933. Multiple disabilities are listed. From census information and other records he immigrated sometime between 1906-1909.
