Looking through some photos taken last summer on a walk by a local canal, when I came across this photo of a single Herb-Robert flower, with creeping Buttercups in a very out of focus background.
Bokeh in a photograph "is the aesthetic quality of the blur produced in the out-of-focus parts of an image produced by a lens" (as defined in Wikipedia and considered a photography art form by the Japanese). Whilst I am not so sure the aesthetic quality is to everybody's taste, I quite liked the effect. I will keep my eye open to try and take better examples this summer (avoiding blurred plants in the foreground as well!)