a target ball
2 balls per scout

Each scout finds two natural 'balls' which can be pretty much anything you can throw - rocks, pinecones, sticks, ..., whatever. Everyone needs to be able to identify their items in a pile of similar items. Maybe color them, scratch with a knife, or tie string on them.

One scout throws the target ball (a rock, frisbee, pinecone, stick) out into the field.
Each player throws his items at the target.
The closest scout receives a point and gets to throw the target for the next round.

Either pass time wandering around the area playing or keep points for determining the winner.