The 1861-O 1/2 dollar is not rare. It does have a unique history though. 333,000 were struck by the U.S. government, 1,240,000 were struck by the state of Louisiana and 962,633 were struck after that state joined the Confederacy. There is still a controversy over telling who did what. The first 2 groups maybe impossible to tell but the latter group were struck as the die began to break so the coins have die breaks. That is small lines on the coins.The coin has a value of $25 in grade good to around $85 in extra fine. That is about what dealers are paying. If your coin has the die cracks it is ore valuable. Remember do not mistake the very rare confederate 1861 1/2 with the 1861-O. There are only 5 originals of the latter.