Where was he living when you had his children? He must have been working and had a drivers lic. if in California they have records that you can access on line. I would start your search in the county where you met him. The 1940 census will be on line soon so you might be able to track him by his census records. I found a Margie Troutt and a Herring in Harris TX. I have not found him yet! I have a roy Morgan but my family is Welsh and not Indian. My Roy married Emma Busby in Alabama. Roy Morgan is not a Indian of Mexican name so he must have a relative name he used.The DNA will give you a lot in information and I will be happy to help you with that search once you get the DNA test done.