MikeInCypress,
If you mean the "Farmer's Market" near 610 North and Airline, that's really, in my experience, a dumping ground for the same produce at the grocery store.
For over a month, there was a hispanic gentleman with a pickup truck parked on Veteran's Memorial/Stuebner Airline just south of Louetta selling watermelons including ones with seeds. Most of them were from Hempstead, TX.
At one point, he had yellow ones. I bought one but the flavor was not great. He didn't not have any orange (Orangeglo for instance).
He did have a half-dozen Black Diamonds (judging from the customary dark green skin and rounder shape) which is what I SHOULD have bought.
Next year, possibly consider the
Hempstead Watermelon Festival.
I am thinking about trying to grow Orangeglo watermelons next year. I can call them my "Canopy-grown Watermelons."