1. try spelling watermelon correctly.
2. try using google.
I found them in 3 seconds.

It looks like a great radish. I've never had any luck growing radishes here in Winnipeg - it gets too hot too quickly. I've tried mustard too - same problem. Joe

The radish is a great taste treat because all the heat is in the peel and underlying white tissue. The "watermelon" pink to red center is sweet, reminiscent of watermelon.

The radish has several names, depending upon the seed company selling this Asian radish. Some call it Red Heart for example. Among those that sell seed are Johnny's Selected Seed and Pinetree Seed.

The tops are good edible greens too.

Botanical Interests offers them so if you know a nursery that carries that line you might find them there. They are called Watermelon Mantang Hong, it's a Chinese winter radish. Rahanus sativus is the botanical name.

Has anyone eaten the leaves?

Yes they are very similar to turnips greens, but even better than turnip roots when cooked in the same manner. The red and green is both tasty and attractive.This is an early maturing winter radish that will make in the spring. Grows better as a late summer fall planting tho.
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Thank you farmerdill. Those look very healthy.