Wills met painter Frida Kahlo and her husband Diego Rivera at the San Francisco studio of her friend sculptor Ralph Stackpole in 1930. Rivera sketched Wills and asked her to model as the main figure of "California" for the 30-foot-high mural "Allegory of California" he was painting for the City Club of the San Francisco Stock Exchange. The committee of the Stock Exchange found out that Wills was being portrayed and insisted that no living person be represented in the mural. Subsequently, Rivera darkened the hair, broadened the eyes, changed the corners of the mouth and angled the jawline to remove any specific resemblance to Wills. A portrait of Stackpole's son Peter Stackpole holding a model airplane remained unnoticed in the mural.