What are the plants next to the steel plates ?

The are a variety of succulents and agaves.

How are the steel plates so even in color? Are they rusted?

No they are not rusted....These plates are painted. Thanks for your question.

What is the type of stones/gravel did you use here?

We used crushed white marble. I hope this helps.

Thanks! Looks great! What size rock is the crushed marble? 3/4" ?

Closer to 1/2".

Where in Houston did you purchase the tree and the white 1/2" rocks? I have been looking in the Woodlands area and no luck!

The gravel came from the Marble falls area outside of Austin. The tree was a mesquite tree. i hope that helps your project.