Do you have your original birth certificate?
Have you applied for any of the non-identifying details that the state will allow you to have?
Have you done a DNA test?
Assuming you were adopted out because you were illegitimate then your mother (marion neumann) may have been anywhere from 15 to 25 years old - so she may have been born between - 1918 and 1928.
Have you looked at census records and family search for women of that name in wisconsin and born between those dates?