There are a number of BUNNOW individuals in FDL's Church of Peace records (most about pre-1945?) which are on microfilm [2 rolls] at the Wisconsin Historical Library, Madison. Not my family, just noticed it.
Mostly baptisms, marriages, confirmations and miscellaneous, plus burial records, which seem to be the likeliest source listing of hometowns and districts in German lands. Most of the handwriting is very legible, whether in German or English.