In the coffee table book, “A Generation Found: Precious Pearls of Wisdom,” Roohee Marshall photographs and interviews 40 gallant, audacious, high-spirited, courageous and lionhearted African American elders ages 80 to 108 from around the country. These Black seniors, which include her uncle, acclaimed photographer Roy Lewis (“Songs of My People”), share their profound lives full of rich experiences that can be passed on to other generations.