All of the pieces below come from part of a clay pipe, what they used to use to smoke tobacco. They would break off bits at a time while they smoked, which is why there are a lot of pipe stems laying around. It's similar to a cigarette butt.
A close-up of a stem with interesting etchings, from the above collection.
Field Specimen 6, unit 2 N 1/2, Strata II, Level 2, 40-50 cmbs