Barred Plymouth Rock chickens, which are also sometimes called Plymouth Rocks or Barred Rocks, are believed to be one of the United States’ oldest chicken breeds. Their heritage isn’t 100 percent clear, as there have been varying reports of crosses, but in any case, Barred Plymouth Rock chickens have long been one of the most popular chicken breeds in the country. Their name was inspired by their beautiful, striped black and white feathers, and they have become favorites on farms and in small backyards due to their calm temperament and egg-laying capabilities.