Juan Aguino is a Pueblo Indian. He is small, muscular, quiet-spoken. He has a way of breaking into soft stutters of laughter. He lives in New Mexico, near two rivers, in a valley of good land and fine old cottonwoods. Yesterday, at the 12th Festival of American Folklife, he stood in a parking lot under flapping green canvas. Fifteen yards away, traffic horned and funed down Constitution Avenue.

"Where are they going?" he says, asking it of himself as much as of the person next to him. "Don't they know it all will wait."

Lesile Wellman used to run a trip motor in a coal mine. He worked 31 years for Island Creek Coal in Logan, West Va., never "mashing more than this thumb." He says this grinning and squinting as an extended paw - a makeshift surveyor. Around his neck is a camera. He has on a Levis jacket. His hair is black and slick.

"I can climb one flight maybe." he says in rolling rural rhythms. "Then I set to breathing heavy." Leslie Wellspan has Black Lung. Where he lives they just call it "lung."

John Thomas is from Temple Hills, aid. he sell vegetables at the Northeastern Farmers Market on Florida Avenue. he remembers when they used to float watermelons and barresl of potatoes down the Potomac to the 7th Street wharves. He also remembers covering his stalls with great sheets of canvas and then putting lanterns underneath to keep the produce warm overnight. "Onions can get cold for two days," he says with a wisdom born of hard work and hard times. "Don't let your potatoes freeze." Thomas says his prices these days are sometimes 10, 15 percent higher than Safeway prices. "But you'd never know the man at Safeway."

What seems wonderful, maybe even wondrous, about the whole 6-day event is that here, side by side, are bread bakers and quilt makers and taxi drivers and sleeping-car porters and oyster shuckers and roughnecks off Texas oil rigs - in all, some 200 participants from 13 states and Mexico - demonstrating unself-consciously the dignity of honest work. As a waterman from the Eastern Shore of Maryland put it Wednesday, "Heck, this stuff is old shoe to us. What amazes me is that people are actually interested in it."

Walking around the festival this week, munching on a National park Service tamale (overpriced and tepid, generally), stopping by a bandstand to hear Mariachi music, pausing to watch a man delicately paint a bird gecoy, one couldn't help feel a great and fine sense of serendipity.

There was discovery eyerywhere here. Not of lost planets or sunken treasures, but of the country herself. Of the things breathing human beings from actual American places do every day of their lives. They don't do them for glory, particularly; they do them for survival. This was a museum, alive, a walk-in story of origins.

At the Museum of Natural History the other day, Harrison Tyler was working on a fish net for crab tanks. He sat straddling a wooden bench, his golf hat askew. He talked in what sounded like Scottish inflections. He is from Crisfield, Md., as was his father before him. His father was a waterman, too - back when it was "slow starvation." Now prices and equipment are better. You can go out year-round. Tyler goes out in his 17-foot wooden Chincoteague shell. Loves that boat, he says.

Tyler has a story that makes him cackle. Two ladies from Baltimore came down to his neck of Maryland one day. They were watching him work with great interest. "Now when a she-crab sheds, she'll go straight to the male to mate. So this old gal from Baltimore, she watches this happen, sees the two of them, the she-crab and the he-crab, wriggling there together, and she says to her friend, 'Now, I wonder what they're doing?' She really means it. That stopped me. Finally, I says, 'Oh, well, ma'am, they're married.'"

Not far from Tyler the other day sat three men explaining to a knot of on-lookers the finer points of tonging and shucking. Two of the men were from Smith Island. They wore country clothes and ball hats. They had the weathered look of salt air on them. Sitting with them, in a charcoal-gray suti, was William Warner of Washington, author of a fine book about men of the Chesapeake called "Beautiful Swimmers."

One of the Smith islanders, a man named Alex, said that a lot of "drylanders" were coming down now. Putting up unwanted buildings along the shores. He shook his head, pushed his hat back. That's when Warner took the microphone and said, "The oysterman's way of life will not disappeaer, I think, as long as there are oysters and crabs in the Chesapeake Bay. He will endure."

A half-hour or so later, in the basement of the museum, in Baird Auditorium, someone else talked of the will to endure. Her name is Hazel Dickens, and she is a coal miner's daughter. Dickens lives in Washington now. The plainness in her face tells of West Virginia, a place she has never really left.

Dickens, who picks and sings and writes hardscrabble ballads about the coal fields (she did some of the music for "Harlan County, U.S.A."), was serving as an emcee for a hastily put together songfest. The music was supposed to be outside, but the weather bollixed that.

"This is grass roots music," she said. "If you want to go to Nashville, that's something else."

She introduced Phylis Boyens. Boyens has curls of jet-black hair. She wore a flower dress, black stockings, strapped shoes. "This first song tells about wintertime in the mountains," she said, launching into a song whose chorus went, "We believed in the family and the old Baptist church/We believed in John L. for a while, 'til times couldn't get much worse."

When she was done, a man named Carl Rutherford picked and sang. He used to work in the mines - til a bad accident drove him out. He sang "Dark as a Dungeon" and "Mansion on the Hill." At one point, he looked over at his fiddle player, nodded, and said: "Get some of that." He also apologized to the audience for the quality of the impromptu performance, which the audience seemed to like rather than resent. "Nine out of ten of use are used to playing alone," Rutherford said. "Now they got nine or ten of us playing together."

When the music was over, Boyens said, "I'm trying to get my record out. I'm going to Nashville to make some cuts."

Late Wednesday, when the sun came out, the focus of events drifted outside, toward the Mall. People sat on red wooden benches, under a grove of trees, their faces ambered by the sun. They were waiting for Agustin Gonzales, his wife, Marilu, and their four sons, Rene, Raoul, Ricky, and Robert, to play their popular Mariachi music. Mrs. Gonzales was dressed in a gay hoop dress. Her husband and the boys wore coal-black horsemen's suits with ornate silver buckles. Gonzales is from the state of Jalisco in Mexico, where Mariachi originates. His sons were all born in America. He is very proud of that.

"We live in Houston now." he said. "I am an electrical designer. That is what I do for my heart."