The Art of Finding
When found objects are used as part of visual art works, the resulting works are referred to as found art.
Early uses of found objects in art focussed on the readymades of artists such as Marcel Duchamp, who shocked the art world with his famous display of a ceramic urinal ("Fountain") in 1917. Pablo Picasso and Kurt Schwitters were among many early proponents of the use of found objects in art, which became an important feature in the work of many schools of art, including the Surrealist, Dadaist, Merz, and Conceptual art movements.
Found objects have gained increasing importance in art over the course of the twentieth century, with many art movements finding new freedoms of expression which had been stifled by the more stringent definitions of art previously used. In the last fifty years, artists ranging from Robert Rauschenberg to Tracey Emin have incorporated found objects into their work either as a main focus of the art or as embellishing features.
 Found objects in music
Found objects are often used in music, particularly to add unusual percussive elements to a work. Their use in such contexts is as old as music itself, as the original invention of musical instruments almost certainly developed from the sounds of natural objects rather than from any specifically designed instruments.
The use of found objects in modern music is connected to experiments in indeterminacy and aleatory music by such composers as John Cage and Karlheinz Stockhausen, although it has reached its ascendency in those areas of popular music most closely aligned with these classical movements, such as the ambient works of Brian Eno. In Eno's hugely influential work, found objects are credited on many tracks. 
The ambient music movement which followed Eno's lead has also made use of such sounds, with notable exponents being performers such as Future Sound of London and Autechre, and natural sounds have also been incorporated into many pieces of New Age music.
Found objects have occasionally been featured in very-well known pop songs: "You Still Believe In Me" from the Beach Boys's Pet Sounds features bicycle bells and horns as part of the orchestral arrangements.
The use of found objects in music takes one of two general forms: either objects are deliberately recorded, with their sound used directly or in processed form, or previous recordings are sampled for use as part of a work (the latter often being referred to simply as "found sound" or "sampling"). With the improvement and easy accessibility of sampling technology since the 1980s, this second method has flourished and is a major component of much modern popular music, particularly in such genres as hip hop.