“It is awful how pleased I am with myself!” So wrote Tchaikovsky to his brother upon the completion of his String Sextet, “Souvenir de Florence.” And he was right to be pleased. Anchoring a program of delectable Russian treats, the Souvenir will be one of many musical memories that listeners will be able to take away from this year’s free outdoor concert on the lawn of the Bridgehampton Historical Society. Bring your family, a blanket and a picnic (Russian caviar optional!) Registration is required; visit www.bcmf.org