This is a painting by Karl Knaths. He was one of America's first modernist painters. Out of an early affection for the work of Cézanne, he let his work evolve into a personal blend of abstract and realist elements, all of it pretty much influenced by the sort of cubist technique that led from those early Cézanne innovations. It's all interesting and mostly good. Art critics, museum curators, and collectors all liked (and still like) his stuff, though not so exuberantly as they like the work of many other American artists (that's why you're probably not familiar with it).
I wrote an article in Wikipedia on him. It's remarkable for snagging only one gripe from that institution's picky editors. She or he put a box at top of the article telling the world that I used too many external links.
I'm fond of this particular painting partly because its owners gave me permission to use it in the Wikipedia article. In my experience owners almost never wish to do this since it requires that they, basically, give up all rights and put the image in the public domain. I'm sure you realize that restrictions imposed by copyright or Creative Commons licenses do little good in keeping protected works off the Internet, but that doesn't make these protections entirely useless and owners are understandably reluctant to let them go.
The painting is called Pumpkin. Knaths painted it late in his career, in 1964. It is oil on canvas, measures 30" x 36" and comes from the collection of the Provincetown Art Association and Museum; gift of Mr. and Mrs. David Orr, in memory of Louise Ault.