Look at form I9.   It has the list of acceptable documents.

If you have a USA passport, you're fine. 

Already, I don't think you qualify.

Being a citizen

Being a permanent resident

Having a visa that allows you to work in the USA

A passport would work for both of those.

If you are not a U.S. citizen, a Permanent Resident Card (also known as a Green Card), an Employment Authorization Document (work permit), or an employment-related visa which allows you to work for a particular employer 

If you are a citizen, you are not required to show any proof by law. A statement that you are a citizen is all that is needed. The employer can ask for a social security card, though there is no legal requirement to show it.

I've never heard of proof of ability to travel internationally. You would need a passport, I assume, but I doubt that they require a passport before you are hired.

"Proof of eligibility to work in the U.S." means ID and proof that you are a citizen or legal permanent resident or have a visa of a type that allows you to work legally. Typically your driver's license and one of the following: a birth certificate for someone born in the U.S., naturalization papers for a citizen born elsewhere, or a green card or visa for anyone else.

If you're an American citizen, you'll need a Social Security card and a US passport.

A US Citizen needs a Social Security card and US Passport.

If you are not a US Citizen, state your situation.

For a typical U.S. citizen, a passport would be what they are looking for.

Passport maybe?////////////////