Green

I reckon it's a path way with a metal edging seperating the grass from the path. and you are taking the picture bent over with the camera pointing down.

Paul

uh?????//

It looks like Paul said.
No matter, what it is, its good !

To spread some light on the issue.
It's a shot puting (http://en.wikipedia.org/wiki/Shot_put) metal ring you see, very old and rarely used by the nearby school.
Thats why it's slightly bent.

The green area is not grass but some other plant, it's a macro pic, shot from about 20cm distance from the object.
The grey is accually wheathered concrete

The grey area of the picture is a separate layer made black and white while the green area and the metal ring has the natural colour.