Tea bags (no tags or string), coffee grounds, egg shells, old baked goods... including bread, cakes and pies; potato peels, carrot peels, banana peels, apple cores and alot of anything else contributes to the cause. Whatever two of us can generate. Probably not less than 5 lbs per week goes in there.
I also add layers of mulch and a very little 10-10-10.
I dont have a tumbler, but wish I did. My composter is fed from the top and I can shovel from the bottom. Which I suppose is good enough for two people.