From Salley Mavor’s show “Bedtime Stitches’’ (embroidery relief) at the Cahoon Museum of American Art., in Cotuit, Mass., on Cape Cod, through Dec. 22. The museum says that this is “a debut of the artist's original artwork for My Bed: Enchanting Ways to Fall Asleep around the World, her children's book about the different ways kids around the world go to bed every night. The book, and her art, highlight and celebrate cultural differences and the universal themes of sleep and safety. ‘‘