I’ve got this question a number of times recently so I thought I would share my typical answers here. Kid friendly means a lot of things to different people. To me it’s a place where you can take the kids that is not necessarily completely devoted to hiking, and has other activities to keep them entertained. Many a parent has taken a trip to Lost Maples only to end up carrying a sleepy kid after about a mile into the trail. If my nephews are anything like other kids then Dinosaur Valley State Park would be one of my top choices. I like this park for a number of reasons; The park has model dinosaurs they can look at, fossils and tracks they can interact with, and a river to fish and play in, and for those that enjoy hiking, a nice bit of backcountry with primitive camping.
Garner State Park: You won’t find dinosaurs here, but there are Basketball courts, Mini-Golf, Paddle Boats, Cabins, a large trail system, and a big river. The cabins are nice for a family that wants to be outdoors but needs some amenities.
Goose Island State Park: Teach them to catch a fish. I remember going out and leaning to fish at a very young age and having a blast. The best part about using the park is that you do not need a fishing license to fish there. There is not much else to do here beyond fishing, but Corpus Christi is about an hour away and offers plenty of other attractions.