The mail brings two pocket dolls, an old lady remembers. . . the Christmas she received Lester and Lynette, gave them to best friend Cordy, her ""Tween""; the Graustarkian novel about the two dolls they composed in alternate chapters; the Washington's Birthday masquerade where all the other girls came as Martha and waltzed, where Cordy and Chrys came as rag dolls and drooped; interludes selling ""aluminy"" tinware with Cordy's boarder, college student Mr. Crump, learning the two-step from Chrys' boarder, college instructor Mr. Banks; ""The Romantical Perils"" found and parodied by Cordy's brothers; a chance to skip eighth grade and go into high school--but are they ""mature enough?"" You might wonder--when they're not playing with Lester and Lynette, these thirteen-year-olds are cutting and pasting pictures and the like, which seems backward even for sixty years ago. But maturity bows in at their first ball; the dolls go to rest properly wed, the girls go on to high school advised that ""perhaps someday you will even write about this very year in your lives in Idaho."" Remembering that they laughed, Crystal Banks sits down to thank Cordelia Crump. . . . Benign if you discount such swellings as swellacious, swelliferous, swellisimous.