I am a permanent residence (green card holder), and I have a social security card. I don't know what I have, because my mother possesses all of my legal documents.
You can get a new social security card, which is required by most employers before you can work.
Your Green Card and Social Security Card should do it.
ask lord obama, he knows the ins and outs to be prez
Go to this link. http://www.uscis.gov/files/form/i-9.pdf It is the I9 form that everyone must complete when they get a job to prove they are legally eligible to work in the US. Scroll down to page 5 and there is a list of the usable IDs.
In your case you will need your I-551 card (Green Card).
You should have that card on you at all times.