When your soil is in good shape, the worms will come. You may need to make it more habitable for them. I would suggest renting an aerator from Lowes or Home Depot and aerating the lawn. Then get a high quality compost from somewhere such as Soil Building Systems (my personal favorite - close to Carrollton, too) and get enough compost to cover your lawn about half an inch. I am very familiar with the ethics of SBS; they have high standards involving their production practices and are extremely friendly to work with. From my many experiences with SBS over the years, I know this to be a company with impeccable integrity. Their compost is incredible! They have many great soil mixes and mulches as well.
I live in Carrollton, and am thankful that SBS is close by! The website for them:
If you go there and talk to Baron, tell him Nadine said hello! (In case you are wondering, I receive no compensation for referrals)!
If you do not have a truck to get it yourself, they will deliver for a charge. Mention that you are a member of the Ground Crew and they will give you a 10% discount on your first purchase. If renting and using the aerator is not feasible, applying the compost alone will be very beneficial to your soil.
If anything toxic such as synthetic fertilizers or that awful product that claims to kill your weeds and fertilize your lawn all at the same time has been used on your property, it would be a good idea to apply zeolite on the lawn. It is sold under the name "Efficient-Z" and is available at Redenta's, North Haven Gardens, and other places. John Silk Feed will order it for you if they do not have it in stock. They are close to Carrollton, too. Smith Farm and Garden in Lewisville (off I-35) carry it as well, if I am not mistaken.