Agrippa,
Your 1976 half definitely is circulated, and 287 million of them were produced in Denver in 1976. The shiny appearance isn't indicative of the coin being uncirculated; it could have been cleaned. The reverse image shows numerous contact marks and loss of luster from circulation.
It's nice to find these in circulation, but unfortunately circulated pieces are very common, and they are worth only face value. That won't change for a decade or so. They do make nice pocket pieces, though. Enjoy owning them.