Lynn Riggs (1899-1954) wrote 30 plays, a few of which were produced on Broadway, along with screenplays and poetry. Nowadays he is known--when he is known at all--for having written Green Grow the Lilacs, which Rodgers and Hammerstein turned into Oklahoma! A gay man and a Native American, Riggs had a strong sense of "otherness" and how it affected people's lives. He often wrote about Oklahoma, where he was born, in t…