Pinkas Hakehillot: Germany: Wuerttemberg, Hohenzollern, Baden edited by Joseph Walk. Published in 1986 by Yad Vashem. 549 pages. (This book is an encyclopedia of Jewish Communities in Germany. It is one volume of a larger set.) This book is entirely in Hebrew, but it has an English Table of Contents. It is available through Yad Vashem. The community of Flehingen is discussed on pages 423-25.
The film(s) for the Jewish records for Flehingen is/are available through the Mormon Family History Centers. A search of the Library Catalog should reveal the film number(s) and details.
If you have any information about the Jewish community in this town or have ancestors with the same surname, please contact me.