It's the stuff that fuels fortune hunters' dreams.

And some of it may even be true. Or not.

For decades, Civil War buffs and assorted fortune seekers have combed the hills and forests of northwestern Pennsylvania, looking for a Union shipment of gold that reportedly was lost near tiny Dents Run in June 1863. Depending on which account you believe, the Union wagon train was carrying up to 52 bars of gold weighing 50 pounds each -- a haul worth some $54 million in today's market.

The mystery so far has yielded little beyond a few vague historical artifacts and a whole lot of stories.

But the Legend of the Dents Run Gold gained new life last week when FBI agents and state officials were spotted digging up the snow-covered ground off Route 555 in Benezette Township, according to CNN affiliate WJAC

"Every once in a while there's a new piece of the puzzle," local historian Jim Burke, a member of the Mt. Zion Historical Society , told CNN on Monday. "And then you think, 'Well, maybe there is something to this thing.'"

Treasure hunters descend

FBI spokeswoman Carrie Adamowski wouldn't say what the agency was doing there, only that FBI personnel were "carrying out court-authorized law enforcement activity in Elk County." She declined further comment to CNN.

But WJAC says their cameras spotted the owners of Finders Keepers USA, a Pennsylvania-based lost treasure recovery service, last Tuesday at the site some 135 miles northeast of Pittsburgh.

Finders Keepers has long been interested in the rumored Dents Run gold. In a post on the Finders Keepers site , founder Dennis Parada says he found a map of the treasure in the 1970s and searched the area unsuccessfully with metal detectors until 2004, when he uncovered a trove of Civil War-era artifacts that they turned over to the state.

"Each time we returned to the site we found more evidence that proved our claim. We found a bullet shell, knifes, animal traps, zinc mason jar lid, tin cans, bones (human or animal), whiskey bottle, camp fire pit, and a lot more ..." Parada wrote. He also claimed his high-powered metal detectors located "a large metal object" 8 to 10 feet underground.

However, the site sits on state land, and it is illegal to dig or remove artifacts without permission.

A purported 2005 memo from the state Department of Conservation and Natural Resources, posted on the Finders Keepers site, says that Parada was banned from doing any further digging at the site. The memo also says the state sent Parada's artifacts to an expert who found they were not from the Civil War era but were merely "hunting camp debris."

Neither Parada nor his son, co-owner Kem Parada, responded Monday to multiple requests for comment. Dennis Parada has recently told other media outlets that he is under FBI orders not to talk.

Some think it's a wild goose chase

In past interviews, Parada has said he is obsessed with the idea of finding the gold.

"There's no doubt in my mind it's down there," he told the Pittsburgh Post-Gazette in 2008. "I'm not going to quit until it's dug up. And if I die, my kid's going to be around and make sure it's dug up."

But experts aren't so sure.

Burke, the local historian, has searched for the gold himself and even hired an investigator to scour government records in Washington.

"We found no credible evidence that there was ever gold there," he said. "There were all kinds of stories going around, but none that we could document."

"There was a tremendous amount of gold that went missing during the Civil War," added author William Rawlings, who has written about a rumored Confederate treasure of gold and silver that went missing in 1865, near the end of the war. ""Most of these (treasure stories) turn out to be nothing."

"It's human nature. We all want to believe that some fantasy is true," Rawlings told CNN. "And people love a mystery."