In 2010, researchers reported on an accidental basic income pilot in which the Eastern Band of Cherokee starting receiving incomes of approximimately $9,000 a year from shared casino income http://goo.gl/ixowfY.

Follow-up in the New York Times describes the results with the observation that “the earlier the supplements arrived in a child’s life, the better that child’s mental health in early adulthood”. http://goo.gl/whjg2Q

The original paper abstract is here http://www.ncbi.nlm.nih.gov/pubmed/20483972