what is the shield on the back of a penny
Penny (United States coin) The United States one-cent coin, often called penny, is a unit of currency equaling one-hundredth of a United States dollar. The cent's symbol is ¢. Its obverse has featured the profile of President Abraham Lincoln since 1909, the centennial of his birth. From 1959 (the sesquicentennial of Lincoln's birth) to 2008, the reverse featured the Lincoln Memorial. Four different reverse designs in 2009 honored Lincoln's 200th birthday and a new, "permanent" reverse – the Union Shield – was introduced in 2010. The coin is 0.75 inches (19.05 mm) in diameter and 0.0598 inches (1.52 mm) in thickness. Its weight has varied, depending upon the composition of metals used in its production (see further below).
Indian Head cent The Indian Head cent, also known as an Indian Head penny, was a one-cent coin ($0.01) produced by the United States Bureau of the Mint from 1859 to 1909. It was designed by James Barton Longacre, the Chief Engraver at the Philadelphia Mint.