On the East Kingdom list, Michel wrote:
"Quite a few dealers but nothing I was really interested in, at least not until I started down one of the last aisles. Sitting on the ground was a piece of wood painted red with the words 'Great Middle Hwy' stencilled on it in yellow. I thought, 'Weird! I wonder what that is from?' I look around and spot two more signs done the same way: 'Brewer's Road' and 'Causeway.'"
Considering this too much of a coincidence, Michel inquired about the signs and was informed that they had been purchased in Philadelphia. Further digging led to seven more including "Street of Gold" (blue on white) and "Cariadoc's Path". The signs were in good condition, complete with Pennsic dirt still intact.
Discussion on the East Kingdom list has revealed that a household in the Philadelphia area is constructing new signs for Pennsic which could explain the appearance of the "artifacts" in a mundane flea market.
Oh, and in case you are curious, Michel bought the signs.