Nearly any plant material, including the following:
Dried leaves, hay, straw, sawdust, wood chips, and shrub and tree prunings. Ned Conwell collects his brown matter, but you can also use straw from a feed store. He puts branches and anything thorny in a separate slow-roast pile in the corner, where it breaks down over a much longer period of time. To hasten composting, chop or mow prunings into pieces 2 inches or smaller.
Green weeds, fruit and vegetable scraps, cover-crop remains, and fresh grass clippings. Also coffee grounds, tea bags, and uncomposted manure from cows, goats, horses, or poultry. Pine needles take longer to break down, while compounds in black walnut and eucalyptus leaves can inhibit growth in other plants; compost those greens only if you combine them with lots of other vegetative waste.
Animal products (bones, meat scraps, dairy products); plants with fungal diseases such as fire blight or verticillium; or seedy or rhizomatous weeds like purslane, Bermuda grass, or bindweed.
Do turn the pile often
After the first two temperature-based turns, the more often you turn your pile, the quicker it will break down into compost.
Do heat it up:
The smaller the pieces, the faster they'll compost. (Run the lawn mower over big, leathery leaves before adding them to the pile.) To check the pile's temperature, Conwell uses a 20-inch-long compost thermometer, available at some nurseries and garden centers and from Peaceful Valley Farm & Garden Supply (from $12; 888/784-1722).