The first two are from from a discussion a while back about using a 2x4 to support the hammock. It worked quite well...I was actually able to swing the hammock. The key is get the 2x4 centered and straight. It would also help to dig a slight hole for the post to sit in. This would eliminate it from kicking out on you. As you can see I placed an eye bolt into the top of the 2x4...just makes it easier to secure the strap. I may experiment with some sort of collapsible contraption that would resemble this the letter (A). It would be much more stable.
The other two are from a beautiful spot I found to hang in the Cleveland National Forest in Southern CA. They were taken in the morning with a slight fog. The tree is a form of the CA Live Oak. I love them.