Nan Wood Graham, the model for the tight-lipped farm woman in the painting, "American Gothic," died Friday in a Menlo Park, Calif., nursing home. She was 91.

The painting caused unhappiness in Cedar Rapids in 1930, when Mrs. Graham posed for her brother, Iowa artist Grant Wood.Local women thought Wood was poking fun at them. The painting portrays a somber, pitchfork-bearing farmer and his equally somber daughter standing before a cottage. The late Dr. Byron McKeeby of Cedar Rapids posed as the farmer.

One woman wrote to say Graham's face would "sour milk."

But after she came forward, identifying herself as the model, the painting gained acceptance and Wood's popularity soared.

Graham's popularity also flourished. If her brother, who died in 1942, had used another model as originally planned, the secretarial school graduate said she would have whiled away her days as "the world's worst stenographer."

Instead, she once said, "Grant made a personality out of me."