We know Halloween is a yearly tradition in America. And when it comes to holidays and festivities, there are all sorts of customs that are part of how we celebrate. "Theme in Yellow" covers all the major bases of Halloween, from pumpkins, to ghost songs, and, of course, those emblematic jack-o-lanterns.
Relax, people. Traditions and customs are just for fun in Sandburg's poem and shouldn't be taken too seriously.
Kids don't give a hoot about traditions; all they're looking for is a chance to have as much fun as possible—with or without the customs.