These are the "M Brace Brackets" and you can find them here: http://www.outdooressentialproducts.com/mbrace.htm The brackets used on this job are the unfinished steel, although they do come in a nice, rich bronze. We (and our clients) have been very happy with them.

Here are a couple more pictures of the product at this job site...

Looks like you added screws to the bracket...was this fairly easy to do? I ask because I want to recommend this product for a do-it-yourself article on raised bed gardening.

Yes, you can use self-tapping screws or pre-drill a pilot hole. We recommend a stainless steel screw for this -- very easy. :) Good luck!

When I bought these M Brace brackets there was no recommendation for screwing them. I can tell you that they are not worth using if you don't screw them. They are sold to work with no screws. Not worth buying. They do not hold the boards well enough and the soil seeps out. I was very disappointed with my purchase.