So when is your actual last day of work? If it was last week or this week and he has offered to pay you till the end of the month, honey that is your severance pay.
Unfortunately, Texas is an "at will" type of employer/employee state and any company can hire or terminate anyone for any reason pretty much. It is extremely hard to prove otherwise. Your employer is NOT REQUIRED to pay anyone severance pay, they normally do, but not always. That last paycheck that you will be getting (if you didn't work for it) is your severance pay. When you hear of someone getting huge severance packages, those are the upper management folks who worked there 15 + years at companies and sometimes it is really not that much.
Be sure and read the form they want you to sign carefully and request a copy of it, so that you can take that with you to the TEC office. The one thing you need to be concerned about is insurance if you have had it through them. If you have been paying for it and it has been withdrawn from your check, then they must offer you COBRA. Which is a govenmentment appointed type of insurance. If you want to know more about that aspect of it, email me at ____@____.com or google it and you can find tons of info about it.
Otherwise, you will have to go the nearest TEC (TEXAS EMPLOYMENT COMMISSION) office and apply for unemployment benefits while you are out of work. This is a very small amount of money that you received from insurance that your company has paid into the government for you and (usually about $150.00 or less) a week based on what you made in your current job. It normally takes up to 3 weeks or more to get the claim processed and get it going, so you will need to do something else if you are depending on that money. You will get paid semi-monthly, so it does take a while to get it going.
Hope everything works out for you and good Luck!