PRESENTS OF MIND: Drew Barrymore's impromptu nuptials to club owner Jeremy Thomas came as such a surprise that her costars in the new femme Western Bad Girls found themselves, embarrassingly, without gifts. ''I haven't gotten her anything yet,'' admits co-cowgirl Andie MacDowell. ''I meant to get something, but what do you get Drew?'' Costar Mary Stuart Masterson also confessed to being stumped. ''I don't think she's registered at Pier One Imports or anything,'' says Masterson. Madeleine Stowe, on the other hand, did have one idea: ''I might just get her a big Texas ashtray.'' Maybe the actresses should just take a hint from Bad Girls executive producer Lynda Obst and stick to something traditional. Says Obst, ''I got her pink champagne glasses and a bottle of Dom.'' Not to worry. Even though Barrymore is a recovering alcoholic who had mere sips of champagne at her wedding, the gift is ''just a keepsake, not something you open,'' says Barrymore's spokesman. What more could newlyweds need?