For lots of Washingtonians, summer begins on Memorial Day, and that calls for a bushel of steamed crabs piled high at backyard gatherings with family and friends. Crabs for sale at Jessie Taylor Seafood at The Wharf in D.C.(WTOP/Kate Ryan) Crabs for sale at Jessie Taylor Seafood at The Wharf in D.C.(WTOP/Kate Ryan) For lots of…