Between 1969 and 1972, Bob Dylan used the ground floor of a building in New York City's Greenwich Village as a rehearsal space. A few months ago, two boxes labeled "Old Records" were discovered inside that building. These boxes contained 10-inch and 12-inch acetates by Dylan that include hand-written notes between the singer-songwriter -- then based in New York City -- and his producer, based in Nashville. These acetates were used in the initial stages of 'Nashville Skyline,' 'Self Portrait' and 'New Morning.'

Essentially, acetates are instantaneous reproductions, recorded live without any editing or production. As music historian Jeff Gold explains, "A blank aluminum disc coated in lacquer is put on a turntable, and the master tape of a recording is played, the signal of which is sent to a heated needle which cuts a groove into into the revolving disc."

Gold is the lucky collector who purchased the two boxes of Dylan acetates. To say these discs are pieces of American music history would be a severe understatement; they are legends in the form of 10-inch and 12-inch pieces of lacquer. In a time where musicians and producers couldn't just email MP3s back and forth, these acetates serve as a tangible part of Dylan's creative process.

As a music historian and collector, Gold runs where he has detailed his findings and is even offering a handful of discs up for sale, including a 10-inch unreleased acoustic version of 'It Hurts Me Too' for $2,500. If you're a collector and interested in securing one of these acetates, get details here.