A single mother whose kids were taken away tries to win them back, while she considers offering another child on the way for adoption. Earth Mama, from first-time filmmaker Savanah Leaf, tells the story of a young Black pregnant single mother in Oakland named Gia, and played by Tia Nomore. Successfully avoiding tiresome exposition, Leaf introduces us immediately into Gia’s world. First we witness her answering questions at an office in Child Protective Services. Her two children, a boy and a girl, were taken into foster care when the office was alerted to Gia’s drug use. She’s been mandated to…