3.5 stars Pablo and Tania Del Valle have moved into a stately fixer-upper in a Washington, D.C., neighborhood. Originally from Chile, he’s a lawyer angling for a partnership at a tony firm. She’s a quite-pregnant Ph.D. candidate in anthropology, whose family has called New Mexico home longer than the state has been a state. In playwright Karen Zacaría’s charmer “Native Gardens,” long-time residents Frank and Virginia Butley greet their younger neighbors with wine, chocolate, chatter.