A woman who paid $7 (£4.35) for a box of trinkets at a West Virginia flea market two years ago apparently acquired an original painting by French impressionist Pierre-Auguste Renoir without knowing it.
The woman considered discarding the painting to salvage its frame, but instead made an appointment to have it evaluated in July by the Potomack auction house in Alexandria, said its fine arts director Anne Craner.
When she pulled the painting out of a rubbish bag she carried it in, Ms Craner was nearly certain the painting was a Renoir with its distinct colours, light and brushwork. A plaque on the front labelled it Renoir.
"My gut said that it was right, but you have to then check," she said.
French handwriting on the back of the canvass included a label and number. Ms Craner turned to the catalogue by French gallery Bernheim-Jeune that has published all of Renoir's work.
"Low and behold, it was in volume one," she said.
An image of the painting was published in black and white, and the gallery's stock number matched the flea market find. So she made a digital image of the flea market painting, converted it to black and white for a closer look, and the brush strokes also matched, she said.
"It's not a painting you would fake," Craner said. "If you're going to fake something, you'd fake something easier."
Painting No 24349 turns out to be Renoir's painting Paysage Bords de Seine, which translates to Banks of the River Seine. It dates to about 1879 and measures 6ins by 10ins.
The painting is set for auction September 29. It could fetch 75,000 dollars (£47,000) or more, Ms Craner said.
Elizabeth Wainstein, owner of the Potomack Co, said there is no doubt about the painting's authenticity.
The Shenandoah Valley woman found the painting and kept it in storage for nearly two years has declined to publicly disclose her name.
After weeks of research, Ms Craner believes Renoir gave the painting to a woman who modelled for him it was later sold to an American lawyer but it is a mystery how it ended up in West Virginia.