Bindweed

This is bindweed - a wild morning glory - of which there seem to be lots of types. This particular plant is growing down at the end of our driveway in what is basically bare dirt and stones. The flower is as large as the morning glories that you grown on purpose - sometimes to your sorrow - from seed. Oddly though, all the ones I have found whilst googling seem to lack the lovely magenta center that these have. Definitely a wildflower, in any case.

Extra is another shot - this time of more of the vine. You can see in that one that the "soil" looks unhealthy at best!