Sightings on the vanishing Indiana persimmon, the endangered Olympia oyster, and the last of the old-time country hams--plus 21 other pieces (with appended recipes) from Sokolov's two years as Natural History magazine's roving food columnist. Most follow a conventional ""folkloric,"" feature-writing line--regional cuisine is rooted in regional produce, now uneconomic (and insufficiently appreciated); so let us celebrate its vanishing glories--and remaining practitioners--while we can. En masse, this becomes somewhat humdrum--though Sokolov is convincing on the superior merits of real Key lime pie (even in the Keys, most are made with the juice of the larger, thick-skinned Tahiti hybrid ""lime""), or the culinary and community value of Allen's Neck Clambake (founded 1888). Sometimes, too, the facts make the story: Maine's lowbush blueberries--the small kind found in muffins--""have to be as laboriously tended as if they were conventional cultivated fields"" (the only thing ""wild"" about them is that the plant propagates itself); now, an expatriate Egyptian--the ""Maine Blueberry Professor of Horticulture"" at the state university--is developing a higher-yielding, cultivable strain to be picked, moreover, by machine. And Sokolov is withholding judgment--as he does also about Minnesota's cultivated ""wild"" rice. All is not, therefore, lost. The best pieces here, though, break out of the mold (a somewhat forced pattern in any case--given Sokolov's non-recognition of either the authentic-foods or rural-resettlement movements). He reports, imaginatively, on moonshining (also endangered, true, but by high sugar prices and the law); he discourses on the socio-cultural lineage of the Finnish-Cornish Meat Pasty (pass-tee, please) of his native Upper Peninsula; and, in another personal vein, he recounts the extraordinary trouble one suburban Jewish family took to ""kosher"" their home. Not Calvin Trillin or John McPhee by a long shot, but agreeable browsing for authentica buffs.