Warning: This story should not be taken as a sign that the little drawing you picked up in Rehoboth and hung over your bureau is worth half a million dollars.

It all started as an urge to houseclean. Last summer an elderly Milwaukee couple decided to clear out some of the old prints and furniture cluttering up their house. They called in an auctioneer, the auctioneer's agent had a sharp eye, and the rest is art history.

A dark floral still life signed with a "V" and hanging in their living room has, you see, turned out to be a previously unknown van Gogh.

"It was amazing," said John Kuhn, the part-time consultant for Leslie Hindman Auctioneers in Chicago, who recognized what he thought was a van Gogh "sort of off to the side" of the Milwaukee living room. It was so amazing that he called his boss, immediately insured the painting and stuck it in his Volkswagen Jetta and drove it to Chicago.

He said he drove very carefully.

Six months later, Han van Crimpen, a van Gogh expert and senior research curator at the Rijksmuseum in Amsterdam, declared the painting to be a minor but legitimate work by Vincent van Gogh painted several years before his suicide. On March 10, the still life will be auctioned by Hindman with a pre-sale estimate of $500,000 to $800,000.

"It's not a masterpiece," van Crimpen told the Chicago Tribune, which reported the discovery yesterday. "It's one of a series of color paintings he did. But it's not very often that a van Gogh painting is discovered, and in that sense this is extraordinary."

Van Crimpen said that each year the museum receives 100 to 150 works allegedly by van Gogh, but that in two decades he had seen only three previously unknown paintings by the Dutch artist.

"The painting in question has all the characteristics typical of the time when van Gogh, arriving in Paris and feeling the need for a lighter palette, painted many still lifes of flowers as color studies," van Crimpen wrote to the auction house. "The flower piece therefore fits well into his Parisian oeuvre of 1886-1887."

Somewhere in Milwaukee, two elderly Midwesterners -- who are not interested in talking right now, thank you very much -- must be smiling.

"They believed it to be a reproduction by another artist of a van Gogh," Kuhn said of the painting, which the couple inherited from a Swiss banker and collector named Gebhard Adolf Guyer. Guyer moved to the United States in 1940, married an American, and when he died in the late '50s left his art collection to the couple.

"They thought it was very pretty and it was their favorite painting, but they thought it was only a copy," said Kuhn. But when he saw it, the picture reminded him of a van Gogh he had seen in a private collection.

"They said, 'What do you think?' and I said, 'You won't believe me,' and they laughed and said, 'Tell us.' "

Which he did.

"I just had a gut feeling," he said, and when he saw that the canvas of the painting was quite old, that gut feeling got stronger. "It's very unlikely that someone would copy a van Gogh that long ago because he couldn't sell any of his works anyway," Kuhn said.

Hindman shared Kuhn's hopes but with a recurring dash of skepticism. "You look at it and you think first, 'It can't be a van Gogh. There's just no way because you wouldn't have a van Gogh here in Milwaukee in someone's house."

But, she said, she pursued the investigation because "it's a very interesting painting in that the colors are rather unusual, the way the vase is painted is quite unusual and the color combinations are sort of strange. You look at it and think this painting was painted by someone who knew something, not just by some flunky -- which is the reason we decided to check it out."

Kuhn said the couple "kidded me that even if it was a van Gogh, they might want it back on their wall because it was their favorite," but the jokes ended quickly and they decided to sell the 16 1/4-by-13-inch painting.

"They're just the sweetest people," Kuhn said, "and they're nice enough to say, 'Look, you found this thing and if it really is a van Gogh, go for it, sell it."

Of course, when he goes for it so will they. Hindman said the estimate of what the painting will bring may be too low. The owners are, according to Kuhn, "comfortable -- they live in a very nice home and I think they have all their needs met." But, he added, "of course, anyone would enjoy having a bonus like this."