In 1946, Dick Fagan returned from World War II to resume his journalistic career with the Oregon Journal. His office, on the second floor above Front Street (now Naito Parkway), gave him a view of not only the busy street, but also an unused hole in the median where a light pole was to be placed. When no pole arrived to fill in this hole, weeds took over the space. Fagan decided to take matters into his own hands and to plant flowers.
Fagan wrote a popular column called Mill Ends (rough, irregular pieces of lumber left over at lumber mills). He used this column to describe the park and the various "events" that occurred there. Fagan billed the space as the "World's Smallest Park." The park was dedicated on St. Patrick's Day in 1948 since Fagan was a good Irishman. He continued to write about activities in the park until he died in 1969. Many of his columns described the lives of a group of leprechauns, who established the "only leprechaun colony west of Ireland" in the park. Fagan claimed to be the only person who could see the head leprechaun, Patrick O'Toole. After Mill Ends officially became a city park on St. Patrick’s Day in 1976, the park continued to be the site of St. Patrick's Day festivities.
Over the years, contributions have been made to the park, such as the small swimming pool and diving board for butterflies, many statues, a miniature Ferris wheel (which was brought in by a normal-sized crane), and the occasional flying saucer. The events held here include concerts by Clan Macleay Pipe Band, picnics, and rose plantings by the Junior Rose Festival Court.
The park had to be moved temporarily in 2006 due to construction on Naito Parkway. It was replaced on March 16, 2007 in true St. Patrick's Day style with the Royal Rosarians, bagpipers, and the Fagan family, including Dick's wife Katherine, in attendance.