Clearly, Adam Sandler was on to something when he sang the praises of a hairnetted hashslinger. Sharon Adl Doost, the U.S. Geological Survey's legendary Lunch Lady, who became an underground phenom when her musical recitations of the USGS' daily fare began attracting some 50,000 calls a month to the agency's menu hotline, appears to be headed for the silver screen. Fledgling filmmaker Leslie Mello recently wrapped more than 30 interviews for a documentary about the 44-year-old cafeteria worker. ''Fans talk about Sharon so passionately. They're so full of love for her,'' says Mello. ''I just wanted to capture that and put it all down on film.'' Mello, who plans to put finishing touches on the film next March, is confident she'll find a distributor. ''I think Sharon taps into something everybody really needs and craves,'' she says. ''And I'm trying to define what that is.'' Mashed potatoes and gravy?