I only stayed 10 minutes at the Alien Masquerade Ball in a ballroom at the Best Western in Roswell, N.M. As the only guest dressed as an Earthling-a polo shirt and jeans-I felt conspicuous among the people boogying in bubble wrap, Star Trek uniforms, and Teletubby outfits, like the "Revenge of the Nerds" cast trying to recreate the cantina scene in "Star Wars." In town for the annual UFO Festival, held every July 4th weekend to commemorate with lectures, parades and other activities the 1947 crash of something in the New Mexican desert, it had taken me all of one day to start feeling like I was the weirdo.

I retreated to the Best Western's hotel bar, where I sat two seats down from a pair of grisled ranchers who could tie for first place in a Sam Elliott look-alike contest. But the two women who sidled up next to me looked out of this world. Literally. They had standard alien heads-large gray faces with long, narrow black eyes, and no noses to speak of. Their robes were made of a glittery material too loose to be aluminum. Each wore a necklace that blinked with multi-colored lights. They ordered drinks--a red wine and a rum and coke.

I introduced myself, and their voices--muffled by the gray masks, but unmistakably female--identified them as Mary Ann and Mo, professional caregivers from the Florida Keys and Ojai, Calif., respectively. The two old friends came to Roswell to visit, and to explore their shared passion for UFOs. Mary Ann told her story of spotting one in the sky above Sedona, Ariz. "It was late at night," she said, removing her mask. She was a rather pretty, middle-aged woman. "I was laying on an energy vortex in a field next to an airstrip. Suddenly, six lights appeared, and I realized they weren't planes but a single, large spacecraft. The ship hovered then shot off into space."

"Mo," Mary Ann added casually, "is into crop circles."

Mo removed her mask, and at first her short, whitish hair and round face reminded me of my mother. "I've visited crop circles in Glastonbury, England, twice now. Some people go for the healing power of them. I meditate in them," she said. "The wheat in the circles, which taste like they've been roasted, give off energy, and it's very peaceful."

This is bad news for M. Night Shyamalan, whose new movie, "Signs," is predicated on the idea that crop circles are terrifying, even if in a spiritual sort of way. The thriller stars Mel Gibson as Graham Hess, an Episcopal priest who loses his faith after his wife dies in a car accident. Soon after we meet him, Hess, his brother, and two kids are spooked out of their minds by crop circles that appear in their cornfield. At first, Gibson's character suspects the bizarre pattern is a hoax. When strange creatures start dancing on his roof, however, he takes it as a portent of an alien invasion. (Click here to read our review.)

Mo harbors no such fears. "Crop circles are definitely alien messages," she explained. "And though we're not yet sophisticated enough to interpret their full meaning, they're definitely symbols of peace. We know this from Native Americans, who created circular symbols as expressions of peace. When they wanted to express anger or violence, they made signs that were jagged, with sharp corners, like hatchets or lightning bolts."

Crop circles are complex, often huge, patterns that mysteriously appear, usually overnight and always in the summer months, swirled in farmer's fields. Reports of crop circles, devotees say, go back several hundred years and they occur all over the world. A 17th-century illustration from Europe depicts the devil spinning what resembles crop circles.

Interest in the formations gathered steam in the late '80s, when the number of appearances and the complexity of their designs began to increase dramatically. Each year more than 250 crop circles are reported from cornfields in Nebraska to rice paddies in Japan.

Southwest England routinely records the greatest number of markings, and some of the most spectacular. The largest formation ever to appear, and it appeared suddenly, overnight, last year, consisted of 409 circles, some 20 to 30 feet in diameter.

Tornadoes, or strange whirlwinds, have been one explanation offered. But the symmetry and elaborateness of the designs--some resemble human and animal forms--discount this. The stalks fall, too, in a tightly woven, cross-hatched pattern. Some suggest psychic forces are at play, induced by vast, unrealized powers of the human mind.

Researchers have put forward laboratory analysis demonstrating cellular changes in crops affected by the circles, changes that can't be replicated by any human means. These considerations, taken with reports of flashing lights and strange sounds, lead others to believe extraterrestrials are responsible for them.

Others blame pranksters, a supposed international gang whose goals are not certain, other than to pull the wool over our eyes. And in 1991, two men claimed they had created crop circles with wooden paddles as a stunt.