Obviously here in Smaug’s lair, Tolkien means that the benches are toppled. I am intrigues to learn that the word can also mean “rotate” as a wheel, to fall to grief or ruin, or to disorder a stomach.
- 13.046 and benches were lying there overturned,
“overturn, v.” OED Online. Oxford University Press, June 2015. Web. 14 July 2015.