If the problem happened to me and the noise sounded like it came from the hub, then I would start dismantling the hub to find out what's rattling. Hopefully just removing the quick-release skewer would reveal the problem, if the problem is in the hub.
If the sound appeared to come from the rim, then I'd take the tire off and remove the inner tube (assuming that it's a clincher tire). The offending object should either fall out of the tire, or you should hear it rattling around inside the inner tube, or the rattling should be coming from the rim itself. If the object were inside the inner tube, I'd replace the inner tube and cut the old one open to find out what caused all the trouble.
It couldn't hurt to check all the spokes; sometimes a broken spoke rattles. With only sixteen spokes, you wouldn't want to ride with one broken or loose.