When you started working in California, you believed you'd be treated with respect. You are slightly older and an immigrant, but this is a land of opportunities. Sadly, what you found was that people often dismissed you because of your background. Your current employer is kind to you, but the coworkers and customers harass you and say negative things about your accent and heritage.
You've talked to your employer about the problem, and he went out of his way to make sure everyone knew the behaviors weren't acceptable. Yet, still today, you're facing discrimination. What can you do?
If your coworkers continue to discriminate against you, you have legal options
It's not just your employer who has to respect you in the workplace. If your coworkers are discriminating against you or harassing you because of your age, color, race, sex, the nation where you were born, your political beliefs, your disability or your religion, you can seek help. You may wish to talk to your employer, since he was willing to help you before. If what he does doesn't help and he is unwilling to terminate the employment of those harassing you, you can file a complaint against the business.
You can file a complaint with the U.S. Department of Labor, and you can also talk to your attorney about filing a lawsuit. In many cases, the threat of a lawsuit could be what is needed to correct the issues in the workplace. No one wants to go to court, since it's expensive and could result in penalties. If that doesn't work, you're well within your rights to sue your employer for the discrimination and harassment he failed to eliminate in your workplace.
No American workplace should support a contentious environment of harassment or discrimination. You deserve to work in a safe, healthy environment.