Let the pictures speak for themselves. For more, go to: http://www.flickr.com/photos/79017140@N08/sets/72157638675490533/
Where mentioned, tree pictures were inspired by Cogdog’s amazing photography on Flickr available: http://www.flickr.com/photos/cogdog/ (CC BY).
Even better, have fun making your own! Just crop an image at an interesting point, copy, transform vertically or horizontally, et voila.