Natural Wood Stains
Rusty nails left to soak in vinegar for two weeks, then strained, make a natural wood stain.
Walnut husks soaked for several days, then strained, stain wood darker than tea. If you don't have a walnut tree in your area, you can get
Black Walnut Hull Powder.
Wood can also be stained with chewing tobacco mixed with half water and half ammonia left to set overnight, then strained.
Any stain should be tested on a scrap of wood or on the underside of a piece of furniture before staining.
Furniture color will darken with each coat of stain. Stop before it looks as dark as you want it to because the finish (shellac, lacquer, tung oil, varnish, etc.) will make the wood color even darker.
See Furniture Refinishing for more information.