Form P-2 is your general form for use when an employer asks that you sign an I-9 form. The I-9 form is for use only for agricultural employees. If you are not employed by a farm or something that is defined in section 3 of the Migrant and Seasonal Agricultural Worker Protection Act, 29 U.S.C. §1802 you do not have to fill out an I-9.

Federal law, 8 U.S.C. §1324a make it is unlawful for a person or other entity to hire, or to recruit or refer for a fee, for employment in the United States an alien knowing the alien is an unauthorized alien with respect to such employment, or to hire for employment in the United States an individual without complying with the requirements of subsection (b) of this section or (ii) if the person or entity is an agricultural association, agricultural employer, or farm labor contractor, to hire, or to recruit or refer for a fee, for employment in the United States an individual without complying with the requirements of subsection (b) of this section.

8 C.F.R. §274a.2 Verification of employment eligibility: (a) General. This section states the requirements and procedures persons or entities must comply with when hiring, or when recruiting or referring for a fee, or when continuing to employ individuals in the United States. For purposes of complying with section 274A(b) of the Act and this section, all references to recruiters and referrers for a fee are limited to a person or entity who is either an agricultural association, agricultural employer, or farm labor contractor (as defined in section 3 of the Migrant and Seasonal Agricultural Worker Protection Act, 29 U.S.C. §1802). The Form I-9, Employment Eligibility Verification Form, has been designated by the Service as the form to be used in complying with the requirements of this section. …
p-2.pdf

Form P-3 is the Citizens Notice. This puts the employer on notice that they have been notified of the law and requests that they comply. Legal action may be pursued in the event of non-compliance.

p-3.pdf