Recommended reading by the National Mental Health Association.    To his mother, twelve-year-old Benjamin Sherman is an object of pity and anxiety. To his father, he is bizarre and embarrassing. To his psychiatrist, he is a case study in mental illness. To the counselors at the camp where he is spending his summer, Benjamin is a "freaky kid" who shuns his peers and is strangely--and perhaps dangerously--attached to his best friend, Elliot, a stuffed letter H.   Through the letters of his sister, mother, father, camp counselors, and psychiatrist--and, most touchingly, through those Benjamin writes to Elliot--this audacious and utterly unsentimental novel gives us a moving and sometimes shocking intimacy with a child whose disorder may be a kind of fragile genius. H is an astute, sympathetic evocation of the state we persist in calling "madness."   "A new and mind-boggling perspective on mental illness from the point of view of the sufferer and those who would love and care about him. . . . H is a very poignant, enthralling debut."--The Boston Globe   "Shepard is a reverse archaeologist, designing a tiny contemporary lost world for readers to excavate. . . . Everything matters. . . Shepard gets everything right."--New York magazine