Nature creates some pretty wild shapes and if you can isolate and focus on those shapes in some clever way, they make great photos. The simplest way to reveal a shape is by silhouetting it against a bright background. Most of us think of creating silhouettes against a bright sky, but it's just as easy to create a shape silhouette against any other bright background--like this field of bright grass on an Iowa farm.
The secret to creating strong silhouettes is to expose for the background and just let the shape go completely black. To shoot this scene I simply metered the bright background, used the exposure lock feature of my Nikon D70s, recomposed and shot. On most digital cameras just holding the shutter release halfway down will lock both exposure and focus--and some let you lock each of those things separately. It's far better if you can lock the exposure and not the focus since that lets you take a reading from the bright area, but still use your autofocus when you recompose the scene.