We had never seen one here, but the Audubon ID book has it listed as present in Texas, and it's host plant is Ruellia, which we have a pasture full of. We "think" it's a white peacock, but can anyone give us a definitive ID? Or just your opinion will be appreciated, also!
It's difficult to tell as its wings are closed. It's either a white peacock or maybe a white admiral. I'm leaning towards a peacock though because of the spots on the under wings. I hope someone else can give you a positive ID.
A great place to ID bugs is this link Bugguide. Then go to ID request I have 100's of pictures there. It is a University and has lots of experts.
We call this butterfly, "distelvlinder"...or "Vanessa". British folks call them "Painted Lady", I believe.
I think Sjoerd is correct. This is my picture of a painted lady, the circles on the wings look the same.