OOLOGAH, Oklahoma - The wet weather over the last week produced an interesting phenomenon across NE Oklahoma.

Huge mushrooms have sprouted in circles called "fairy rings." A good example showed up over the weekend in the lawn of the U.S. Army Corps of Engineers project office at Oologah Lake.

"Mushrooms are the spore-producing structures of a fungus, which grows underground or in decaying debris," said Ranger Matt Nolen. "Fungi are not plants. They are in a classification kingdom entirely of their own. Mushrooms often appear after rains, when moisture levels are optimum."

According to the Missouri Botanical Gardens web site, the organic matter fairy rings break down is often old tree stumps and other larger pieces of organic material buried in the soil. Several fairy rings may appear close together, especially on lawns that exist on sites that were previously wooded areas. When this happens, you'll notice fairy rings do not cross each other, because fungi quit growing when they contact each other.

As the name implies, fairy rings are the subject of folklore in many parts of the world. Some cultures consider them a mark of danger, while others link them with good fortune.

One of the largest rings ever found is near Belfort in France. It's about 2,000 feet in diameter and is is more than 700 years old.