Seed swaps are sprouting up everywhere, giving home gardeners a chance to score free seeds and seedlings from each other while discussing what grows best (and worst) in their neighborhoods, streets, and even blocks — taking locavorism to whole new levels. Most swaps in this area have been inspired by the Berkeley Ecology Center’s annual swap — this year’s was the eleventh — where live bluegrass hoe-down music and a potluck feast accompany the changing-of-hands of thousands of seeds representing hundreds of varieties of fruits, vegetables, flowers, legumes, ground covers, trees, and more. It’s held in late February to give gardeners a head start on the post-frost, pre-spring peak planting season — and its founders belong to the seed-saving movement, devoted to preserving heirloom varieties that might otherwise vanish from existence as corporate seed companies increase their dominance over what’s available for sale. Seeking a seed swap in your area? Ecology Center volunteers can help you find one.