You need to prove your immigration status.
Do you want to know how to do it?
Yes please, tell me.
You have to provide us with your current U.S. immigration document. The forms I-551 Lawful Permanent Resident Card, Machine Readable Immigrant Visa with your unexpired foreign passport and  I-766 Employment Authorization Document, EAD , work permit are good to show.
And to prove my age if I can't find my birth certificate?
We could ask you for another suitable document, like your passport or a document issued by DHS as evidence of your age.
And how can I prove that I lived outside the US?
You can use your current or previous passport or show us your school records or work records from the country you used to live.
what if I don't have permission to work but need the social security number to apply for government benefits?
You can actually apply for a social security number if you are required to provide your social security number by a state or local law to get general assistance benefits.
What would happen if I use a non-work social security number for work?
You shouldn't do it but if you do it we would inform the DHS.
Is there another document that I can use to prove my immigration status?