Looks like a mulberry seedling...
I did some reading about osage orange last year (or whenever) after someone mentioned the mamoths... The Trees That Miss The Mammoths - American...
I'm thinking solidago canadensis
Where in Texas are you? Considering the other plants... I have to believe that you have the Chinese variety....
1) mimosa (invasive) 2) oxalis... (wood sorrel) aggressive. 3)looks like an apple. (if you are asking about the ground cover, a closer pic is...
Possible rubrus odoratus?
saplings look like Calycanthus... but their fruit doesn't seem to match what you have there.
Commelina...
Pilea?
iberis?
Cardamine? http://the3foragers.blogspot.com/2012/03/hairy-bittercress.html
The leaves look like Paper mulberry (Broussonetia papyrifera). The flowers... actually look like maybe a Galium climbed up the limb...
While "star of bethlehem" can be a little too successful for a flower bed... If all I had was turf... I'd be all in favor of the flowers crowding...
looks like possible Impatiens.
Looks like yarrow, a turf alternative. They say.. That you should mow when it starts to bloom... Personally, I'd wait till the blooms had peaked...