Superstitions; The Sad Lament of Pecos Bill on the Eve of Killing His Wife. Theater pieces by Sam Shepard. Directed by Julie Hebert. It may be questioned whether Sam Shepard is so important a contemporary playwright that even his scraps and rejects deserve full productions. But the double bill recently assembled at La Mama makes a good case in that direction.
''Superstitions,'' first performed by the Overtone Theatre of San Francisco in 1981, was written as a collection of prose and poetry for a Shepard book. Working with the author, the Overtones adapted the snippets into what they call ''a play with music, mistaken sounds, and silences. A day and a night on the desert.''
''The Sad Lament of Pecos Bill on the Eve of Killing His Wife'' was written for - and rejected by - the Bicentennial Committee of San Francisco in 1976. A sort of comic operetta about ''the first cowboy of all time,'' it was eventually performed at a California theater festival and has now been resuscitated by the trusty Overtones.
How do these fugitive pieces look on stage at La Mama, as presented by New Writers at the Westside, the Overtones, and La Mama itself? Most presentable indeed: lively as can be, and crammed with the unlikely combinations of bravado, nostalgia, farce, and Wild West mythology that have become a Shepard trademark.
Both works feature two performers, Mark Petrakis and O-lan Shepard, who are admirably in tune with their material. In the first part of the evening, ''Superstitions,'' they glide through a string of monologues and dialogues with a tread so light they hardly leave tracks on the desert their words evoke. Some moments are whimsical, others poignant, or even a little scary. Sam Shepard sees plenty of romance in the desert, but his vision is sardonic enough to include all kinds of incongruous characters, from homey couples to a hard-bitten loner who listens to the stillness of the night and figures a nuclear meltdown must be going on. It's an odd blend of moods, with an impact as sharp as it is subtle.
''Pecos Bill'' makes a rip-roaring contrast to all this, belting out the tragicomic romance of our hero and Sluefoot Sue with makeshift melodies and broad choreography. Again, there's a touch of sadness to even the most rollicking moments, as Bill wonders why he and his spouse, once celebrated in myth and legend, are now turning to dust in the otherwise-occupied American consciousness. But at the rare moments when things threaten to become just a tad philosophical, the energy and wit of the performers quickly remind us that it's all in fun.
Catherine Stone is musical director of the evening, providing gossamer background sounds for ''Superstitions'' and joining a quintet of country-and-western players for ''Pecos Bill.'' Both pieces are inventively directed by Julie Hebert, the fourth member of the Overtone troupe, which sees its mission as ''reinventing the musical'' by devising seamless, up-to-the-minute scores based on a variety of popular styles. In all, a modest but engaging evening.