These are called "cobblestone" pavers, and they come in many sizes and shapes to fit various designs like circles and straight-a-ways. They can also be tumbled to give them a worn look. Most hardware stores sell them.

Thank you. I did some more research and found "circle patio kits" at Menard's. My local Lowe's and Home Depot did not offer online or in-store kits, but one manager offered to call his vendors and check. It would save me a trip out-of-town to the Marion Menard's. Again, thanks.

Several of the main manufacturers do these kits including Pavestone - http://www.pavestone.com/plaza-stone-iv-circle-pack-60mm/

Thank you so much for the exact website. I tried Pavestone from a pamphlet from Home Depot, and it gave me just one product, and I couldn't find anything about circles from there. Thanks again