Folk music instruments run the gamut from found objects to instruments that have been developed by highly skilled craftspeople. If you're looking to start a folk music band and don't know what instruments to include, here's a quick and easy guide.
What we call a banjo probably evolved from an instrument brought to America by African slaves, called banzas, banjars, or banias. Since the slaves weren't permitted to play drums, they started making banzas. Originally, these were made from a dried gourd. They'd cut the top off the gourd and cover the hole with pig, goat or cat skin. Then, they'd attach a neck made from wood, and usually three or four strings.
A dobro is an acoustic guitar with a metal resonator built into its body. This resonator serves as an amplifier. In contrast to acoustic guitars, the placement of the resonator takes place of the sound hole. Therefore the shape of the guitar doesn't tend to have an affect on how the dobro's sound is amplified.
The fiddle is a mainstay in all styles of traditional and rural music, from classic-style country to bluegrass, folk, and roots rock. Though it is technically the same instrument as a classical violin, the way the instrumentalist plays it differentiates between "fiddle" and "violin." World Music Guide Megan Romer has a deeper look at the history of the fiddle.
The harmonica is, aside from the human voice and your own two hands, the most portable instrument used in traditional American folk music. Most harmonicas are small enough that they fit perfectly in any pocket. With a body that's typically constructed of wood or plastic and a metal cover plate, the harmonica operates by a set of reeds that vibrate when you blow or suck air through any of the 10 holes.
Despite the Jew's harp's name, there's no apparent historical connection with Judaism. Many older cultures fashioned it out of bamboo, while metal bow-shaped versions came from throughout Europe and Asia. It's one of the oldest known instruments, and is traditional to cultures around the world.
The history of musical spoons goes back as far as does the history of the spoon. Cultures from Russia to Ireland to Native American cultures have a history of playing the spoons or spoon-shaped bones. Some people think the playing of the bones was part of a spiritual tradition that loosed the spirit of the animal, or channeled the animal's positive spiritual benefits.
The musical washboard is a percussion instrument played by scratching or tapping the metal washing surface up and down in rhythm. Players often guard their fingers with thimbles or metal guitar finger-picks. The washboard is a popular percussion instrument in all kinds of folk musics from around the world, but is most often seen in America in the context of jug bands, old time music, and zydeco.
Washtub bass is a musical instrument that traditionally has one string that is plucked, using a metal washtub as a resonator. The string is tied at one end to the washtub and, at the other end, to a stick or staff (often made of wood). The player will moved one hand up and down the staff, "fretting" the string, while plucking it with the other hand in rhythm similarly to how one would play a bass guitar.