The stories seem to vary a bit in the level of maturity needed. I've used the story of Humpty Dumpty with preschoolers, but I wouldn't think "Tom, the Piper's Son" would work that young. This tale of the theft of a pig seems meant for school-age children.
By the way, Baum also wrote a rather unusual look at The Life and Adventures of Santa Claus. This creative look at familiar stories and rhymes are great starters for encouraging children to try the same. Later this month we will see yet another author's take on such expansions when I post Madge Bigham's Stories from Mother Goose Village.
This is part of a series of bi-weekly posting of stories under the category, "Keeping the Public in Public Domain." The idea behind Public Domain was to preserve our cultural heritage after the authors and their immediate heirs were compensated. I feel strongly current copyright law delays this intent on works of the 20th century. I hope you enjoy discovering new stories.
Currently I'm involved in projects taking me out of my usual work of sharing stories with an audience. My own library of folklore includes so many books within the Public Domain I decided to share stories from them. This fall I expect to return to my normal monthly posting of a research project here. Depending on response, I will decide at that time if "Keeping the Public in Public Domain" should continue along with my monthly postings.