I do not know them all but I know the Chi. bears, N.Y. giants, Cin. Bengals, Chi. cardinals, Phi. Eagles, Pit. steelers, and GB packers are what i can think of. There are two teams that played in the first season of the NFL (1920) that exist in 2008. They are the Decatur Staleys, now known as the Chicago Bears and the Chicago Cardinals, now known as the Arizona Cardinals. The Green Bay Packers entered the NFL in 1921.
There are three: The Arizona Cardinals are the oldest, founded in 1898 as the Morgan Athletic Club in Chicago. The Chicago Bears (originally the Decatur Staleys of Decatur, IL) and Green Bay Packers (who have been the Green Bay Packers since their founding) were both formed in 1919, one year before the NFL, although for some reason the Bears consider the day the NFL was founded to be the day the team came into existence.
It was the 1972 Miami Dolphins.
The Broncos This Year HaHa
1920
In 1995 the bear owner started a new team and they name it Ravens and move to Baltimore
dallas cowboys
It was founded for the American Football League, but the NFL made a stronger offer for the team, so the team waited until 1961 and became an NFL team.
The Chicago Bears (George S. Halas)
The Dallas Cowboys were an NFL expansion team in 1960.
The Cowboys joined the NFL as an expansion team in 1960.
The Vikings joined the NFL as an expansion team in 1961.
The team that wins the super bowl that year.
In the 2010 NFL Draft, that is the Washington Redskins.