Agha Fat ali, not much "must see" places in DFW area. Just good restaurants and shoppings. Kasra is not bad, it is buffet (boofeh), there is another Iranian restaurant called Giovanni on Preston Road with very good ghormeh sabzi and khoreshte bademjoon. Having said that you out to try some real good Tex-Mex, cajun foods and real barbecue.
Austin and San Anton which are about 3.5 hours drive from Richarson is much more fun place.