I'm also in Texas, 8a, and have all of these growing in my fields
First is definitely wild morning glory... I fight with it every year because it has tried to consume my
greenhouse and other structures (and drops thousands of seeds each fall).
I always thought the second one was lambsquarters. Glad to learn that isn't the case.
The sapling (third) appears to be a young cedar elm. The
wood chips I used on the garden last fall was full of cedar elm berries, so I've been chopping them out of the garden all spring and summer.
The common name for the last one is straggler daisy. It makes a pretty dense ground cover in the fall. I believe I've seen my geese munch on it, but they'll eat almost anything, so I can't say it's not toxic.