I live in California where the minimum wage is 8 dollars an hour, and I just started working at a flea market where I get paid forty dollars a day working from 6:00AM to about 5:00PM, is this legal?
I recommend you contact the Workers' Rights Clinic with the Legal Aid Society of San Francisco's Employment law center. The link is http://www.las-elc.org/clinics.html. You should also contact the California Labor Commissioner's Office.
If you believe you are not being paid in full, you could file a claim with the Labor Commissioner office local to you. You would be entitled to back pay, OT, penalties and interest, and attorney fees if you win in court.
If serious about hiring counsel to help in this, and if this is in SoCal courts, feel free to contact me.