Well, actually, a PTO that is conducting business under 501(c)(3) charitable status is accountable to the state and government, and has to follow its state's corporation laws (for nonprofits, of course). Part of this involves submitting articles of incorporation and bylaws to certain agencies like the state's attorney general's office (check your state's guidelines for non-profits), and bylaws must also be on file with the IRS.
California Corporations Codes can be found at this website:
California Corporations Code
You can "Google" your state's laws by typing in your state's name followed by "corporation codes" (or "laws"). Look for the section that deals with "Nonprofit Corporation Laws." The codes will tell you what is required of a nonprofit corporation, how to incorporate (if you are not) and who to file what with.
They also spell out the responsibilities of the Board of Directors, term limites, membership, meetings, etc.
I hope this information helps you!