The good, gray Trillin hangs up his prose pistols and rides forth as Poet in his seventeenth book, here collecting three years of comic political verse for The Nation. Best known for his Americana and true-crime stories in The New Yorker, for his fabulous food reportage from Kansas City, Louisiana, and elsewhere, and for Remembering Denny, his 1993 bestseller about a friend who committed suicide, Trillin may be a national treasure for his journalism as well as for his two witty one-man shows, which prompted Mel Gussow to dub him ``the Buster Keaton of performance humorists.'' Must doggerel be crude, unpolished, a dog's verse? Though the opening pages of his yappings leave something to be desired, his skills increase with use, although Trillin's funniest moment isn't poetry; it's his complaint about losing Alexander Haig as a fit object of ridoggericule as he watches Haig, like Shane on his white horse, ride out of town, leaving behind little Brandon de Trillin shouting, ``Haig! Haig! Please don't go, Haig! We need you, Haig! Come back, Haig!'' Trillin's father, a Kansas City restaurateur, devised rhymes for his menus (``Let's go, warden, I'm ready to fry/My last request was Mrs. Trillin's pie''), lending young Trillin a rhymer's background. Aside from a bouquet of general doggerel (``New movies, which are mostly dumb, are in the summer/Even dumber''), his subjects, not always treated fairly, he admits, include George Bush, the Reagans, Ross Perot, Mrs. Thatcher, Gorbachev, Clarence Thomas, Clark Clifford, Arafat, Clinton, Gore, Kuwait, and Saddam (``This guy who often said he'd smash us flat in one battle/Turned out to be what Texans call all hat and no cattle''). Let's call it fiddle faddle/between wisdom and a baby's rattle.