Anyway, rhode - I honestly don't know what you'd do in this situation. I wonder if there's some rule about not throwing away old passports that no one pays attention to or realizes and we're supposed to keep them all... anyway, if I were in your position I'd contact the US Department of State, tell them what you need and why, and see if they can do anything to help.
Original Nationality: US
Visa #1: PMV (300) through Washington, D.C
Applied: April 2013.
Visa Granted: January 2014.
Visa #2: Subclass 820 (From PMV).
Applied: End of April 2014.
Visa Granted: Early July 2014.
Visa #3: 801 (PR)
Eligibility Date: End of April 2016 (Applied a month prior).
PR Granted: Early April 2017.