Baum was interested in acting, for one, but his literary interests started when he and his brother produced their own journal at home in their teen years. Then, in March 1880, he established a month periodical — The Poultry Record. The content was based in large part on competing journals in the trade, with the exception of Baum's editorial content. He sold the magazine within a few months but continued contributing a column, "The Poultry Yard." The journal's publisher, H. H. Stoddard, collected some of the popular musings into a book in 1886: The Book of the Hamburgs: A Brief Treatise upon the Mating, Rearing, and Management of the Different Varieties of Hamburgs. This manual for fancy chicken breeders was, apparently, printed without L. Frank Baum's permission. It was, nevertheless, his first book.
A few years later, Baum moved with his young wife to what is now South Dakota (a landscape he translated into Kansas in his famous novel). From his Book of Hamburgs:
For the first week, perhaps, nearly every old hen is faithful to her little brood, and guards them with that maternal tenderness for which she has been made the symbol of mother love. But this care soon wearies her, and in a few days she begins to neglect them, marching around in the chill and drenching rains of spring, and dragging her little brood after her through the damp grass, entirely oblivious of their sufferings; and one by one they drop off.
*For information in this post, I am indebted to L. Frank Baum: Creator Of Oz (2003) by Katharine M. Rogers.