Several pieces that I wrote in the late 1960's and early 70's come to mind. In particular, Four Haiku Sketches and Ten Events for Band, two pieces for concert band. There was also an extended piece for double quartet (classical woodwinds and jazz ensemble) as well as several pieces for experimental theater. As I write these words, more originals and arrangements are coming back into my mind. I did A LOT of writing during those years!
At this stage in my life and in how my music has evolved, it is likely that I would no longer care for those earlier pieces. However, some of them might have stood the test of time and would be like meeting old friends again. Regardless, what's gone is gone. I am entirely happy to have all of the music that I have written since 1989...more than 30 years worth. When I think about the pieces that I no longer have, I can see how they served as a foundation for the music that came later. From this perspective, nothing is ever lost.
UPDATE: I just discovered that the score for Four Haiku Sketches is in the University of North Texas library. It is part of the Source: Music of the Avant-Garde collection. The score is in Series 2: unpublished scores. oversize, Set 1; Box 1 Barcode 711602. I have submitted a request to the UNT music library to receive a copy of the score. I will post another update here when there is a reply from the library.