Municipality of Schwienau (Samtgemeinde* Altes Amt Ebstorf / Uelzen
County / Lower Saxonia).
Its ratio is 3:5. It's a green over white horizontal bicolour superimposed
by the coat of arms.
Description of coat of arms: The shield is divided by a light blue
(FIAV-code B-) fessy wavy line with a white roundel on each side. The chief
shows the green leaf of a linden tree in a silver (=white) field. The base
shows a big silver (=white) stone (germ: Findling) in a green field.
Source: I spotted the coat of arms on 28 March 2007. The image of the
flag was made according to Hauptstaatsarchiv Hannover, where the
flag was submitted on 13 February 1981, so described in http://kommunalflaggen.de/.
*A "Samtgemeinde", also called "collective municipality"
is a combination of several municipalities to an administrative community in Lower Saxony.
Klaus-Michael Schneider, 9 April 2007