International Potato Center
"The International Potato Center - (CIP) is a not-for-profit, autonomous scientific institution established in 1971 by agreement with the Government of Peru. CIP is one of 16 international research and training centers supported by the Consultative Group on International Agricultural Research (CGIAR). The CGIAR is sponsored by the Food and Agriculture Organization (FAO) of the United Nations, the United Nations Development Programme (UNDP), the United Nations Environment Programme (UNEP), and the World Bank, and comprises more than 57 countries, international organizations, and private foundations." source - CIP
Find Heirloom Sweet Potatoes at the Following Farms
Duck Creek Farms' website provides descriptions of many of the varieties of sweet potatoes that they usually provide for shipment from late spring till early summer.