Promoter Amy Yetman, who test-ran the concept of the Horseshoe Market — a classic flea market crossed with a quality craft fair — on a sunny day last October, couldn't have hoped for better results. Called "horseshoe" because of the object's lucky connotations, the market offered nearly 100 booths of sheer serendipity: s, handmades, jewelry, clothing, plush toys and just about anything else one could imagine. It rocked the Berkeley 'hood like nobody's business. With that under her belt, Yetman's opted to bring it back for three Saturdays in 2011, beginning with a spring market on May 7. Be there or be square.