If you are a collector of militaria, buttons are an important part of history. The manufacture of military buttons has been thoroughly researched and excellent records are available for time of use. If you collect paperweights, a great selection of miniature paperweight buttons is available. If you collect art miniatures, the painting under glass found in buttons is a match for your treasures. Many stamp collectors have found buttons to pair with their stamps.
Coin collectors can often find old coins which have been made into buttons.
Most anything you can find in the world of antiques has been duplicated on buttons. The eagerly sought-after turned handkerchief corner button with a wallpaper background and an escutcheon of a boy in a boat in high relief. Buttons come in such a variety of materials and subjects that it would be impossible to name them all. Here it can be said that materials go from A for aluminum to Z for zinc - and that includes such odd materials as bread dough, butterfly wings, chicken skin, hair and wax. Subjects cover just about anything imaginable and it would be easier to name the subjects not covered than to list those covered.