Have you checked the given names database on Jewishgen.org for suggestions?  Also remember that when you look in the US censuses there were times when Poland did not exist, it was either Russia (eastern and central) or Germany/Prussia (western).  Many people Americanized their names by using the first letter.  I have seen many instances of the name Sam when the Hebrew/Yiddish name was not Shmuel.  No idea of Filda - could the name have been Tilda?