If you mean stuff that will go all the way home... Not much. If it weighs more than a couple ounces I will probably mail it home. Even if it weighs almost nothing I'll mail it home if mailing anything else.
I used to pick up more stuff for use on the trip, but have lately limited that to mostly only what will be used in the next couple days. On the TA we kept picking up packets of condiments and stuff and realized that we probably had a couple pounds of them. Actually my daughter was the one who realized it, since she was stuck carrying them. She said "if you guys want to keep this stuff you can carry it". We immediately pitched most of it and stop collecting stuff.