Available through URI's cooperative extension for the cost of shipping.
https://web.uri.edu/mastergardener/freeseeds/
Description from the site:
"Burpee® seed packets are available for the cost of shipping and handling to individuals, schools and other nonprofit organizations in
New England, Pennsylvania, New York and New Jersey through the generosity of Ocean State Job Lot, which donates still viable 2019 seeds for the 2020 growing season to URI Cooperative Extension annually. Orders are filled by URI Master Gardener volunteers; we thank you in advance for your patience once you place your order, as our operation is volunteer-staffed. Please allow four weeks for delivery if you are ordering by mail. Learn more about the Free Seed Program by reading this article. Happy Growing!"