I have to hand it to Canton. They hit on something back in 1965 when they let some artists hang their work on the courthouse fence and sell it.
I would imagine nobody that day had any idea that 57 years later the courthouse lawn, downtown, and streets would be covered by thousands of vendors.
The Canton Flea Market is always on the second Thursday of May and October. There are always new vendors every year, as well as the regulars.
Be prepared for a lot of walking, and bring something to carry your stuff in.