Fun stuff! I've been in some crawl spaces, but never found anything but shards. Of course I've heard the stories of what one can find though! I hope you get lucky.
Some friends of mine that live in New Orleans used to "crawl houses" a lot. New Orleans has a very high water table so the privy's are very wet and very shallow. A lot of people just tossed the "hard trash" bottles cans etc under the house.The Crawl spaces these guys dug over their life time held some wild finds. They are 67 and 70 years old now they dont crawl anymore but they do float around the construction lots. I hear their story's every time I call.
Die hards all the way