Donut peaches, also known as Saturn peaches and flat peaches, are a variety of peach known for their distinctive shape.
Originally developed in China, the donut peach is a freestone peach (the most common kind sold in the US) that has been specifically bred to grow into a flat, nearly toroidal shape. Like the freestone peach, a donut peach still has a pit (or stone) at the center and is roughly 3 inches (7.5 cm) in diameter. It is said that you can simply push the stone out since it is always visible, but this can be quite a messy ordeal. It is easier to simply eat around the stone or to carve it out with a paring knife.
This shape of peach is still rare in the US, as US-safe breeds started to appear on the west coast in only the 1990s. Other states that grow peaches, including Georgia and New Jersey, started to grow donut peaches more recently. For folks like me in Western Pennsylvania who live far from peach orchards, donut peaches are fairly expensive: yesterday (August 2) I bought two for 89¢ each. At Whole Foods Market in Pittsburgh, I bought three for $4.73 -- $1.57 each, or nearly as much as regular peaches cost in Tokyo!
If you can find the means, I highly recommend picking up some donut peaches. Because they're smaller (overall) than normal peaches, all the juicy flavor is packed in even tighter than with a normal peach. They're very, very sweet, and much healthier than the type of doughnuts you might find at Krispy Kreme. I've only seen them in July and August, so get 'em while the gettin's good!