I work at a restaurant in California and I was on payroll roe half of the hours I worked, and was paid the other half in cash (my hourly wage). Taxes were taken out of the cash I recieved, but were not recorded on my w2 form, nor did the owner claim my tips that I made. I have not yet filed my 2004 taxes because I do not know how to go about this. For a full time job it shows that I only made 5000 dollars for the whole year. Not to mention the fact that some days that I worked were 15 hour days with no breaks and no overtime pay. How do I go about finding out my rights on this subject, and is this conduct illegal?

Do your taxes now. If you have to amend them later you have up to two years.
It doesn't sound too legal. It would be nice if you kept records of your hours worked on a calender or some sort or ledger. Sometimes if you use the same pen on the calender or ledger the judge thinks you made it up.
Your boss probably feels paying you in cash helps you too. It is my understanding that if you make less than $6,000 a year that you get all the money you paid in taxes back in your refund.
When you retire your social security check will be less because it says you made less. Also your boss is making it look like your working part-time saving him money on workers compensation insurance and payroll tax.
It would probably be in your bosses best interest to pay you because the franchise tax board would cost him much more.

No decisions should be base on these statements. These statements are only ideas that may or may not be worth looking into. The poster is not an attorney.