Seems you got your answer over on the Fruit Forum. :)

Rodney

Here is a link that might be useful: Is this true about watermelon seed saving?

Watermelons, melons, tomatoes and peppers can be eaten at a nice ripe stage and the seed can be saved at the same time.
On the other hand, eggplant, summer squash, cucumbers, beans and peas cannot be eaten and the seed also saved.

I was eating a "seedless" watermelon and found a mature seed. The following spring I planted it. I had glorious vines, flowers and eventually a watermelon. It looked exactly the same as the parent.

That fall, when I opened it, not only did it have ridiculously little red pulp but it had so many seeds that nothing was edible anyway!