Seriously, my new favorite place to eat with the kids! Freebirds just opened up a new location in Lewisville across from Vista Ridge Mall and kids eat free with the purchase of an adult meal Sundays after 3pm and all day Monday and Tuesday each week. My husband and I took our kids and we each ordered the 2 taco combo (comes with chips and a drink) and the kids ate free – $10 and some change for a YUMMY meal! Check it out and tell them My Dallas Mommy sent you! 
(14 locations in the metroplex – go here to find one close to you.)
The freebirds on 7th street in Fort Worth also has kids eat free for the same days and times.