I picked up a pack of 100 brown paper bags, and I just write the "treasures" on the front. You could have them hunt for anything. I like to write out different colors, because Rowan knows his letters enough to be able to sound the words out and figure which color it is that he needs to look for. 

Rowan actually asks me to make these up now...he loves them so much. And Crew is happy to follow him around and pick up leaves and grass to stuff in a bag of his own. We have done this several times now, and I have found that it is a great way to entertain them for a hour our so. I even did it inside once when I needed to get some housework done. The options are endless!

If you give a try, let me know how it goes...I would love to hear what "treasures" you come up with!