I haven't lived in DFW in 4 years ... but still visit for family.
ANYWAYS, Check out the Dallas Arboretum
Link ->>
Dallas Arboretum
I've shot there... lots of great places.
How about any good parks?? If you are close to North Dallas there is White Rock Lake ... great place.
Or even a nice playground and get your child enjoying his childhood on the playground.
Get shots of him on a swing set, down a slide, on the teeter-tooter.
Hope this gets your creative juices going ... and happy BDay to your son.
-Ray-