Butterfield is a town near Uncle Henry's Kansas farm.

When the Shaggy Man first met Dorothy Gale, he asked her the way to Butterfield so as not to go there by mistake. He claimed that if he went there, a man would try to repay him fifteen cents and he didn't want the money. Later he admitted that he had stolen the Love Magnet from a girl in Butterfield. (The Road to Oz)

Background

There are a number of American towns named Butterfield, but none are in Kansas. There is a Butterfield, Missouri, but it is far enough from the Kansas border that it is unlikely for Dorothy to walk there. L. Frank Baum's Butterfield appears to be fictional.