I picked a seedless one today. I know these are common at the grocery.
The local feed store doesn't have seedless watermelon seeds. They were hard to get for me and expensive at $6 per 10 seeds. I planted my watermelons a month late and didn't get many but still got two dozen. Last year I had them by 4July but this year more like 01Aug.
I also planted seedy watermelons. I don't mind the seeds. Last year I had over 50 melons and the vines were planted as ground cover between my citrus trees(Beaumont,TX near Houston.)