It's possible that the first time you behold the luminous, lemon-haired Mamie Gummer will be on Broadway, in the Roundabout's production of Les Liaisons Dangereuses, where you will watch the dastardly Valmont ravish her, deaf to her convent-girl entreaties. Or maybe you will catch her in the Tribeca Film Festival, where she appears in the romantic short All Saints Day as a mascara-bleared Tinkerbell, making the walk of shame the morning after Halloween. Perhaps you already saw her in Stop-Loss, as the young wife of an Iraq-war vet; or in John Adams, on HBO, as the president's long-suffering daughter-in-law, Sally. But chances are, whether or not you know it, you most likely encountered Gummer long before this prolific April, in the 1986 movie Heartburn, when she appeared as a 2-year-old on the hip of her actual mother, Meryl Streep, and on the lap of Jack Nicholson, who played her dad.
"Bless," Gummer says on the balmiest, sunniest morning of the spring, upon being reminded of that early role, as she sits in a café, awaiting her cranberry scone. Now 24, she's wearing what on a toddler might be called a sunsuit: navy cotton short-alls sprigged with white horseshoes, a matching white T-shirt, red cloth sandals, and an antique charm necklace--gold-plated Victorian penknives ("An old boyfriend gave them to me")--on a chain. She looks, in a word, adorable. "You know," she confides, "I still get residuals from Heartburn. A couple times a year I get a check for $80. I love watching that movie. Whenever I'm having a bad day, me and my sisters turn it on."