I get my copper pieces from http://basiccopper.com/. She has an eBay site as well. If you call and ask her, she will sell you scraps or maybe even a sampler pack. You can get a lot of good pieces for jewelry from scraps. To color/patina it, I use a solution from Volcano Arts http://volcanoarts.biz/cart/metalsmithing/index.htm. It is called Oxidizing Solution. Liver of Sulfur will do the same thing, but it stinks.
To create the texture, I used my bench block, hammer, and the letter "O" from my alphabet metal punch set. You can get that from Volcano Arts or even eBay. I just randomly hammered the letter into the copper. It does curl up a little. I keep it on the side that I hammered in the letters and use the rubber mallet on it lightly. The piece flattens out without great loss in puffiness. I turned it over so the puffed out portion was my top side. I used my finger and dabbed some black paint on the texture. I wiped off the top of the letters to give it some contrast. I then took some Golden's interference green oxide fluid acrylic and dabbed over the black acrylic paint. It is a trick I learned. It gives it a great aged color. You can seal it with a spray sealer so that little pieces of paint won't later peel off of the metal. I only do it if I am going to wear it a lot and it will rub on stuff.
Another way to create texture is using a rubber mallet and glue gun dots. You can get a rubber mallet at any hardware store. You use a rubber mallet when you want to straighten/flatten out metal without making marks on the metal from the hammer edges. Heat up your glue gun. Randomly put glue dots on one end of the mallet. Let cool completely. Take the glue strings off. There are always trailing glue strings. They stay on pretty well. Once in awhile, a dot will fall off. I just stick a couple more on. So, one side is for texture and the other side is for flattening metal. Put your piece of metal on a hard, even surface. I use a bench block. You can get it at Volcano Arts (buy the larger one, trust me) or you can get it online at eBay or places like Harbor Freight. If you get it from Volcano Arts, then get the rubber mat, too. It really does help to muffle the noise. Back to the metal texture. Just bang on the metal with the textured side of your rubber mallet. If it is thinner metal, closer to foil, then you might want to back it with a heavier gauge piece of metal or something else. If you don't want the metal to lose its puffiness, you can apply a thin coating of light spackle to the back side in the grooves to hold the texture.
Hope that more than answers your question.