I have been extremely lucky in the half dollar department.  These Walkers were found over the years in various places.  They are a real "heart pounder" when they pop up.  I haven't found one in quite a while as they are getting harder and harder to find.  It is not easy to miss a half due to their large size (in comparison to missing a dime).  I have found as many as two in one day, and have been fortunate enough to do that twice.