Vintage postcards adorned with rustic landscapes, spooning young lovers, and wish-you-were-here greetings are the jumping-off point for this uneven but affecting series of vignettes of early-20th-century America in Had A Good Time. Sometimes the tone is wryly comic, as in ''The Ironworkers' Hayride,'' where a shy accountant and a woman with a wooden leg express romantic longing in a discussion of female suffrage and Halley's comet. Occasionally, Robert Olen Butler strains for contemporary relevance: In ''The One in White,'' a brief flirtation between a Mexican laundress and an American reporter during a U.S. military incursion comes off as a too-obvious allegory of not-so-innocents abroad. Yet in the standout ''Carl and I,''a librarian reaches out to her consumptive, dying husband with clear-eyed, aching poignancy.

