Read this excerpt from "The Medicine Bag.”

All I could do was stand there with the whole neighborhood watching and shake the hand of the leather-brown old man. I saw how his gray hair straggled from under his big black hat, which had a drooping feather in its crown. His rumpled black suit hung like a sack over his stooped frame. As he shook my hand, his coat fell open to expose a bright red satin shirt with a beaded bolo tie under the collar. His get-up wasn’t out of place on the reservation, but it sure was here, and I wanted to sink right through the pavement.

Which is a symbol of the grandpa's heritage in this excerpt?