Let me start by saying that there is indeed a $.50 piece in the United States currency which started with the Ben Franklin half and went to the Kennedy half dollar. To you naysayers out there, go to wiki and discover for yourself.
As a coin collector myself, any Half Dollar coin would likely be worth more than $.50 because of its age. if it was in mint condition, (no scratches, mold. . .) than it would be worth even more than 50 cents.