I wanted to post a bit about these, but wasn't sure what they were called (hence last night's question).

(click for bigger view)
These beauties are cornflowers and I spotted them growing between a couple of pieces of stone at the edge of a small hump in a field.
I'm not absolutely certain, but I believe from the few pieces of stone scattered around and the associated hump of earth, the site once held a dwelling of some kind.
I've checked maps of the local area, but so far have not turned up any reference to a house having been present in the location... so now I'm clutching at straws a bit.
Does anyone know if these cornflowers grow naturally in rocky ground, or would you expect to find them in an open field? Perhaps more to the point, are these flowers native to the UK, or would they have been deliberately grown from seed?
I'm hoping they may be an indication of once cultivated garden...
Any ideas folks?