Shelley is a city in Bingham County, Idaho, United States. The population was 3,813 at the 2000 census. The mascot for the city's high school is "Boomer", a russet-burbank potato that wears a crown, robe and scepter. Since 1927 Shelley has been home to the "Idaho Annual Spud Day", which is celebrated on the 3rd Saturday of September. It typically features a parade, live bands, games (such as a tug of war into a pit of mashed potatoes) and free baked potatoes.