The price of copper had gone up in the 1850's and the mint decided it simply cost too much to produce the larger copper one cent pieces of the day. Cost is still in an issue for the mint over 160 years later, as the price to make a modern penny is now a little over 2 cents.
This lead to two big changes with coins of this era. The first being that the half cent coin was abandoned in 1857 and the smaller Flying Eagle replaced the large cent. In 1856 a pattern coin was shown to members of Congress, and this had a mintage of just 2,000 coins. The coin only survived for 2 more years, as problems with the design created by James B. Longacre led to cracks in the dies and was a difficult to manufacture.
Below are three of the coins I purchased at the local coin dealer. One has a hole that reduces the value but I thought this was a unique and inexpensive example to add to the collection.