After retiring from truck driving in 1987, Teri Horton devoted much of her time to bargain hunting around the Los Angeles area. Sometimes the bargains were discovered on Salvation Army shelves and sometimes, she willingly admits, at the bottom of Dumpsters.

Even the most stubborn deal scrounger probably would have been satisfied with the rate of return recently offered to her for a curiosity she snagged for $5 in a San Bernardino thrift shop in the early 1990s. A buyer, said to be from Saudi Arabia, was willing to pay $9 million for it, just under an 180 million percent increase on her original investment. Ms. Horton, a sandpaper-voiced woman with a hard-shell perm who lives in a mobile home in Costa Mesa and depends on her Social Security checks, turned him down without a second thought.

Ms. Horton’s find is not exactly the kind that gets pulled from a steamer trunk on the “Antiques Roadshow.” It is a dinner-table-size painting, crosshatched in the unmistakable drippy, streaky, swirly style that made Jackson Pollock one of the most famous artists of the last century. Ms. Horton had never heard of Pollock before buying the painting, but when an art teacher saw it and told her that it might be his work (and that it could fetch untold millions if it were), she launched herself on a single-minded post-retirement career — enlisting, along the way, a forensic expert and a once-powerful art dealer — to have her painting acknowledged as authentic by scholars and the art market.

She is still waiting, defiantly, for that recognition and the payoff it could bring. But as a kind of fringe benefit, her tenacity has made her into a minor celebrity, a pantsuited David flinging stones at the art world’s increasingly wealthy Goliaths. Now it has also landed her the starring role in a documentary scheduled to open next week in New York and later around the country, called “Who the #$&% Is Jackson Pollock?” (When Ms. Horton asked this of her art teacher friend, the original question included a word that cannot be printed in this newspaper nor, apparently, blown up on movie marquees.)