Is this a lawn disease?
There was not sufficient details to be sure in the photos you submitted. For what can be seen, it seem that you have a bermudagrass lawn with a bunch of weeds. It is possible that weeds are numerous because of thin grass coverage due to some thing contributing to poor health of the turf.
Would suggest that you contact your local Texas A&M AgriLIfe Extension county office in Tarrant County *http://tarrant.agrilife.org) to see if they may be able to help with more conversation and requesting of more details to help make an educated guess.
If disease is suspected, I would even suggest submitting a sample for diagnostic analysis. (see http://plantclinic.tamu.edu for submission forms and fee schedules).