Here's an un-complete list of compostable items (remember, the list keeps getting bigger as new things are invented!):
Coffee grounds/ coffee filters
Hair from your brush
Jello (pure gelatin)
Cupcake/muffin cups (paper only, can't be composted if they have no-stick spray)
Your pet's fur/bedding
Pickles
Used/unused paper plates without a wax finish
Ashes from a fire pit or fireplace
Elmer's glue
Eggshells
Newspapers
Old paper towel/toilet paper rolls
Peanut butter without any oils, hydrogenated or not
Sticky notes
Any unwanted or spoiled dairy product, but only in small amounts
Sawdust
Old leather gardening gloves and other leather products (make sure they're real leather, and, if possible, they should be ripped up into smaller pieces)
Thin cardboard
Undyed/untreated cotton products
Some food wrappers (only if labeled "compostable" or "biodegradable" - the newer sun chips, for example)
Lint from the dryer
Cooked rice/pasta if there's nothing but water on it (no olive oil, salt, etc.)
Nut shells (NOT walnuts - they can be poisonous to some plants)
Nail clippings
Dry fish/dog/cat food
Used matches
Ivory soap shreddings
Shredded papers (no staples!)
Stale crackers/ cereals(if there's little to no sugar added)
Pencil shavings
Pits/seeds of any vegetable or fruit that you didn't grow yourself - store-bought produces' seeds won't grow a new plant because they're genetically engineered.
Click here for a more complete list by category or here for a longer unsorted list.