I put some very small versions of evergreen conifers in mine. One tall one and three spillers. They lasted several years before they were too big for the pot and lack of water did them in. I added some annuals inbetween. I can't remember the varieties off hand, but they were ones that if you walked into a big box and picked up a little one, there you had it!

ETA: One Leyland Cypress and three blue rug junipers. All were the little starter plants.

Asparagus Fern, Ponytail Palm, Aglaonema, Angelwing Begonia, Spathiphyllum, Boston Fern ....... Think house plant.

Variegated Aspidistra

I am a garden designer but I live in Illinois- so I am not sure about Austin- however if you buy what is perennial in Austin you will not have to move it in and out if there is a freeze. Just make sure your container is bigger than the plant. Maybe find a small ornamental grass.