1) Baum framed the pencil he used to write the book. He framed the pencil stub and hung it on the wall in his study. On the attached paper he scrawled, "With this pencil I wrote the manuscript of The Emerald City."
2) He got the name "OZ" from his filing cabinet. At first, Baum had trouble coming up with a name for the magical land Dorothy visits. Then one day he found himself looking at the filing cabinet in his study. There were three drawers marked "A to G", "H to N," and "O to Z." And so Oz was born.
3) Dorothy Gale was named after a niece who died. Dorothy Gale is based on Dorothy Gage, the infant niece of Baum's wife, Maud. She died in November 1898, right as Baum was writing The Wonderful Wizard of Oz. The character Dorothy was Baum's tribute to the lost baby girl.
4) Dorothy's shoes were silver, not ruby red. In the book , Dorothy is given "silver shoes with pointed toes." The color was changed for the 1939 movie starring Judy Garland because the filmmakers thought that ruby red looked better in Technicolor.
5) The book sold out in two weeks. Full distribution began in August. According to the publisher, the first printing of 10,000 copies sold out in two weeks, followed by a second printing of 15,000 and a third printing of 10,000. In November, there was a fourth printing of 30,000 and in January, a fifth printing of 25,000. That's 90,000 books in the first six months. The Wonderful Wizard of Oz remained a bestseller for two years.

Citations
"13 Facts About L. Frank Baum’s 'Wonderful Wizard of Oz'" Mental Floss. N.p., n.d. Web. 15 Sept. 2016.

"The+wonderful+wizard+of+oz+novel+1900 - Google Search."The+wonderful+wizard+of+oz+novel+1900 - Google Search. N.p., n.d. Web. 15 Sept. 2016.