In 1921, Wiggin and her sister Nora Archibald Smith edited an edition of Jane Porter's "The Scottish Chiefs", an 1809 novel of William Wallace, for the Scribner's Illustrated Classics series, illustrated by N.C. Wyeth. During the spring of 1923, Kate Wiggin traveled to England as a New York delegate to the Dickens Fellowship. There she became ill and died, at age 66, of bronchial pneumonia. At her request, her ashes were brought home to Maine and scattered over the Saco River. Her autobiography "My Garden of Memory" was published after her death. In sorting through material for her autobiography, she put many items in a box she and her sister labelled "Posthumous." Her sister Nora A. Smith later published her own reminiscences, titled "Kate Douglas Wiggin as her Sister Knew Her," from these materials.