Yama Yama Land: Where Everything is Different is a 1909 children's book written by Grace Duffie Boylan, and illustrated by Edgar Keller (1868–1932). It is a noteworthy example of an Oz imitation, a story taking many elements from L. Frank Baum's Oz books by another writer and illustrator. It's also an unusual instance in which an Oz imitation was issued by Baum's publisher. Reilly & Britton advertised Boylan's volume as "An Extravaganza in Book Form for Children."
Boylan was a friend of Baum and of W. W. Denslow. Her story bears a clear resemblance to Baum's fourth Oz book, Dorothy and the Wizard in Oz: Boylan's heroine Sylvie enters a magical underground realm through a fissure in the Earth that opens during an earthquake. In Yama Yama Land she encounters cities of lost things, which suggests the Valley of Lost Things in Baum's Dot and Tot of Merryland.
In the century since its first publication, the book has attracted attention and praise more for Keller's illustrations than for Boylan's story. Keller's illustrations include fourteen color plates, two of which are double-page spreads.
Boylan's novel was inspired by a comic song of her era, "The Yama Yama Man" (1908).