Georgia O'Keeffe holds a stone that friend Eliot Porter found on a rafting trip they took together. She said she’d stolen it from him. Years later Porter told writer Terry Tempest Williams that O’Keeffe visited for Thanksgiving dinner after the trip. The stone was in his living room, and while the Porters were in the kitchen, it disappeared. "The next time I saw my black smooth stone," Porter said, "it was in the palm of O’Keeffe’s hand in a photo by John Loengard , in LIFE magazine."