I am not sure whether the US government has your documentations in custody because it was long time ago. The prison administration may have some circumstantial evidences regarding their visitation to you or contact information of the ICE agents. At least the agents will have some records such as copies of the supportive documents they found in their further investigation according to your allegation. You may ask the immigration officer or ICE agent you will meet for any information about your permanent residency, such as alien number, the name of the city where you lived when your application for Green Card was submitted, the date of approval of your residency.
