As an employee in the United States, you have the right to be paid for the work that you have done regardless of your legal status. An employer cannot refuse to pay wages for work performed simply because an employee does not have a work permit or a social security number.
You also have the right to be paid for the work that you have done regardless of whether you have signed an employment contract with your employer because such rights are provided under federal and state wage and hour laws. If you have signed an employment contract with your employment, such contact may define the underlying wages to which you are entitled.