The three figures in the lower foreground of Agate's drawing appear to be playing the game Meriwether Lewis described in his journal for February 2, 1806:
One of the games of amusement and risk of the Indians of this neighbourhood, like that of the Shosones, consists in hiding in the hand some small article about the size of a bean. This they throw from one hand to the other with great dexterity accompanying their opperations with a particular song which seems to have been addapted to the game. When the individual who holds the piece has amus-ed himself sufficiently by exchanging it from one hand to the other, he holds out his hands for his competitors to guess which hand contains the piece. If they hit on the hand which contains the peice they win the wager; otherwise they lose. The individual who holds the piece is a kind of banker and plays for the time being against all the others in the room. When he has lost all the property which he has to venture, or thinks proper at any time, he transfers the piece to some other who then also becomes banker.
A similar game was played–and still is–among all Indian peoples in North America.
Stewart Culin, Games of the North American Indians: Volume 1, Games of Chance (Lincoln: University of Nebraska Press, 1992).