La Playa Maya is a fabulous little Mexican joint on the northwest side of Fort Worth. This place was originally somebody's house, but they've turned it into a quaint little out-of-the-way restaurant that is really a delight to go to.
Their chips and salsa are just great. I don't know what they fry those chips in, but they are addictive! And the salsa is good on everything.
For a cheap and filling lunch, try the Cheese Enchilada plate. For $4.45, you get two cheese enchiladas covered with meaty chili, rice and beans. They will top them with onions upon request. This and a glass of water gets you out the door for under $5!