When asked why she wanted to be a Playmate, brown-haired Sally Sheffield candidly replied: "It would be a monetarily rewarding way to build up my ego." But even a cursory examination of Sally's variegated curriculum vitae shows that this talented New Yorker hardly requires such psychic therapy. A dedicated horsewoman since childhood, she has won an array of awards for her equestrian ability--including being judged one of the top ten riders in Manhattan's prestigious National Horse Show at a precocious 16. Sally, who is as accomplished on the piano as she is in the show ring, minored in music at Massachusetts' Wellesley College (where she took her bachelor's degree in psychology), then went on to Boston's New England Conservatory of Music, earning both a master's degree in musicology and a teaching fellowship in English literature. "Though I love books," she says, "I love music even more. The piano is my serious instrument; but for fun, and to learn folk songs, I also play the guitar and the autoharp." (For our less musicologically oriented readers, the latter is a zitherlike instrument that produces chords rather than individual notes). Her musical inclinations helped prepare her for a part-time career as a folk singer in Boston coffeehouses and landed her a leading role in an NBC television series for children titled The First Look, for which she also co-authored the music. "Although I'm a dropout from the Ph.D. program at the conservatory," Sally says, "I'll probably wind up teaching music history at some point." Her goals for the immediate future are far from professorial, however: "I suppose my ambitions are not really unique--to enjoy good health, happiness, a solid marriage and a career to keep me from stagnating. I try hard to guard against mental laziness, because I'm convinced my mind will wither if I don't keep it exercised." Sally wishes she had more spare time to globe-trot ("I did spend eight months working in an Israeli kibbutz--artificially inseminating hens, of all things--but next time, I'd like to be a camera-toting tourist"); to learn another language (she's already fluent in French and Hebrew); and to consume more books. Her literary tastes range from Joseph Conrad and T. S. Eliot to her all-time favorite story, The Wizard of Oz. "But as fond as I am of fictional wizards," she says, "I want my real-life hero to be flexible and fun-loving, though he should be stronger willed than I am--to keep me in line. What I look for most in a man is personal integrity; Moshe Dayan and Adlai Stevenson earned my admiration because of their courage and their honesty." When not daydreaming about her ideal man and free-lancing as an actress-folk singer, Miss May divides her time between the riding academy and her West Side pad--writing music, catching up on her reading and sharpening her culinary skills. Her idea of a perfect evening at home is an elegant French dinner à deux (from escargots bourguignon through crepes suzette) followed by lazing cozily before an open fire. With Sally Sheffield as a companion, that would approximate our idea of a perfect evening, too.