I use a combination of burlap bags (coffee bean bags that we get that has fabricated pipe in it), and the bark off of cedar trees that have been cut for a little while (fence post). the burlap lights quick and easy and the cedar bark will smolder for a long time.
In a pinch......hay, dead grass, pine needles, sisal baling twine, anything natural just look around.
When I had some really hot bees I would go to the barn and get some left over tabbacco leaves and add that also, seemed to work really well for calming them down a notch or two.
G3