No Cambodians.....only Loatians.
There was a small population of Cambdians around Jimmy's food store in East Dallas. Not sure if there are any families still in that neighborhood. I would go scoping out that area for food. Make friends and see if you get an invite to dinner!!
I went searching for a Cambodian restaurant after I returned from a vacation in Siem Reap but couldn't find anything. Hopefully someone has a good recommendation. However, is there a specific dish you're looking for? It's possible it could be found at a Vietnamese or Thai restaurant around town.