Browsing through Amazon I discovered this executive toy designed to replicate stonehenge on your work desk. But I'm a wargamer so immediately saw a potential for turning it into scenery.

Contained in the box are 18 standing stones, a paper mate to place them on and a booklet about stonehenge. Well didn't bother with the booklet and the mat wasn't very well detailed.
The stones are quite nicely detailed but the plastic is fairly soft so removing the few mould lines were a bit of a problem. Used a knife in the end rather than a file.

You can see the stones as they are out of the box next to some 10mm fantasy miniatures from Pendraken the scale is quite nice compared to 10mm miniatures. It might work with 6mm or 15mm.
I didn't want to recreate an entire stonehenge for gaming with so I divided the stones up into two batches.

I created two standing stone sections for use with my 10mm undead armies. I based them on some strips of plastic card in a crescent formation.

They were very easy to repaint and a good, quick and cheap way to make scenery.