You've got a lot of resources here, but I want to add one more. Basically because they are here in the hinterlands with me, they do great work, and they are big Slow Food supporters.Seed Savers - Decorah, Iowa
They have a fantastic selection.
Also, if you want to continue having
heirloom seed to use, you may want to read about a recent Supreme Court decision that will make it possible for Monsanto and their ilk to take utility
patents on seed varieties. That means that is your heirloom tomato get cross pollinated by your neighbors "Round-up Ready" tomato, the seeds you save will have a Pioneer Hybrid patent, and you'll owe them money if you plant them. Swear to God.
Read more about it at this link:The Barons Are at Court