These photos are composites. Each of mine are two images combined in some way.
The photo above is the first composite I have ever done on photoshop. As you can see, it is a bit rough around the edges--literally. This was our assigned abstract composite. The sign and the guitar are both part of my first photo assignment.
This was the second composite I completed. I cut out the hydrant from a different picture and pasted it on the "NO BALL PLAYING" wall. The biggest issue I ran into here was lighting. Since both pictures had alternate light sources, it was difficult to make the hydrant look natural. In any case, I flipped the image and burned the wall to do my best to combine these images in the most natural way possible.
The above photo was my third and most convincing composite. I cropped the bricks from a different photo I had previously taken. After I pasted it, I had to scale, skew, and distort it to make it take the curve of the artillery shell naturally. I then burned around the edges to make it seem like this was a sunken part of the photo. I like this one the best of the three.
All in all, this was a very good exercise. As you can tell, my images got better as they went along. It helps when you learn the keyboard shortcuts and you become more used to the tools available.