This is the oldest known film version of The Wonderful Wizard of Oz, made in 1910. It was made by the Selig Polyscope Company and did not involve the author, L. Frank Baum.

Smithsonian Magazine has an article called Frank Baum, the Man Behind the Curtain. It describes how Baum came to write what amounted to the first American children’s book and how he was so convinced he’d written a great book that he framed the pencil stub he’d written it with.