I think that 'Greenfield' (or Grün(en)feldt) would be in Russian something like 'Zelenopolevoy' or '-polevaya' if female, stress on -vo/va. I've never met such a name but again that guarantees nothing!

In imperial Russia since Ekaterina II's days, the jews were allowed (in principle) to live only in towns in a zone that reached from the Black Sea to the Baltic (present day's Ukraine, Moldova, White Russia, Poland, Lithuania, Latvia etc). Most of them spoke Jiddish as their mother tongue, so names presumably were mostly Jiddish also.

And to be precise, Spy, it's 'Lebedev' that translates litarally to 'Swanson' (being the old possessive form meaning 'of swan').

AKS