The first one I used was Flickr Colr Pickr, found here. It was so cool! I was a bit disappointed that some of the photos were just fields of (essentially) solid color, instead of being particular objects having said color. Ah well.
I did find a really cute pink photo, though! I couldn't figure out why I couldn't save it onto my computer. Turns out, it's copyrighted. I thought all the photos on this 3rd-party site were for public use! In case you are curious, you can find it here. I just love the color, the texture, and how close the objects seem to be to the camera.
Next, I was super excited to try out the trading card creator! Try it, you'll love it! For some reason, regardless of what portion of the photo I chose to be visible if cropped, the trading card creator rotated it. Again, things didn't go exactly as I planned, but I actually like the result: