Yes it is a thing. A full size replica of the real Stonehenge located in Natural Bridge, VA. It was built by artist Mark Cline to the specifications of the real Stonehenge. We stopped once on our trip down south and it was quite a site. There are many stories about who built the original Stonehenge but of them all, I like to believe that it was Merlin the Magician and his friend the Giant.
Note: After I wrote this, I discovered that Foamhenge was moved from its Natural Bridge location to Cox Farm located in the DC Suburbs. The foam stones have been repaired and repainted and it looks very real.