On the verge of the road called Gorselands in our village of Sedlescombe there is an astonishing colony of sweet violets (Viola odorata) with pale and dark colour forms.
This is not a native of our area and I suspect the original plants were imported with turf, probably from the South Downs, used to make the verge.
We also get small colonies of V. odorata var. praecox which is I think always a garden escape here. It flowers earlier than the nominate subspecies and has smaller, darker flowers. Both types, of course, have that wonderful scent.