Twice a year, the valley's growers gather in a church basement and trade seeds the way other people trade stories. A jar of scarlet runner beans for a twist of dill seed. A brown envelope of tomato seed with a note that reads, simply, grandmother.
None of these varieties are in the catalogues. Many of them are older than the people handing them over. The exchange works on trust: you bring what you saved, you leave with what you will grow, and you promise to save again.
This spring we followed a single packet of pole beans from the basement to a hillside plot and back. The bean is not rare in the technical sense. It is rare in the way that matters: someone has kept it alive, on purpose, for eighty years.