Seattle - Mysterious crop circles have appeared in an eastern Washington wheat field - not far from the nation's largest hydropower producer - but area farmers preparing for the summer's harvest find the distraction more amusing than alarming.

"You can't do anything other than laugh about it," said Cindy Geib, who owns the field along with her husband, Greg. "You just kind of roll with the theory it's aliens and you're special because aliens chose your spot."

Friends called the Geibs on July 24 when the pattern of flattened wheat was spotted off Highway 174, about five miles north of the town of Wilbur. The field is about 10 miles south of the Grand Coulee dam, which the Bureau of Reclamation says is the largest hydropower producer in the United States.

The circles resemble a four-leaf clover and remind Cindy Geib of Mickey Mouse ears. The design knocked down about an acre of their wheat. Some of it could be salvaged by combines when the harvest starts in a week or two, she said, but some will be lost.

"Of course, we don't have alien insurance," she said.

Crop circles have been a worldwide phenomenon for decades, and this is not the first one in Lincoln County. Similar circular patterns were left in crops in the Wilbur area in 2010 and in 2008 or 2009, Geib said.

Lynne Brougher, public affairs officer for the Grand Coulee dam, hadn't heard about the latest crop circles but said the previous one was no cause for alarm.

"It seemed to be highly unusual," Brougher said. "As I recall from a couple of years ago, there was no good explanation of how they got there."

Still, she added, "it wasn't a concern."

The latest crop circle was first reported Tuesday by Spokane station KHQ-TV. There were no signs that anyone walked into the field.

"We're trying to figure out how they got out there without breaking any of the wheat. It's hard to walk through the crunchy wheat and not knock it down," Geib said. "At the same time, it's hard to think it's aliens. It's a bizarre thing to wrap your brain around."

Geib's daughter-in-law, Kelly Geib of Wilbur, says the crop circle has given the family something to ponder and chuckle about.

"The kids all like to say the aliens have come, and we're happy to indulge them," she said.