Every seed has a story to tell, if someone will listen. This week, I asked Sara Straate, the seed historian for Seed Savers Exchange, to come on the show and explain the work that goes into tracing the history of heirloom seeds that, in many cases, came to the exchange after being saved for generations by home gardeners. Seed Savers Exchange in Decorah, Iowa, is one of the country’s largest non-governmental seed banks, with more than 20,000 varieties in its ever-growing collection.