Plymouth is a city in Amador County, California, United States. The population was 1,005 at the 2010 census. The town was originally named Pokerville, when it was settled during the time of the gold rush. Plymouth is commonly now known as a "Gateway to Shenandoah Valley", a popular wine-producing region in the Sierra foothills. Plymouth is home to the number one Country County Fair in the state of CA and to a wonderful community of people who value their rural lifestyle.