I've been making ice wreaths for a few years now. They are so pretty, and if you live somewhere cold they might actually last a while!
All you need is a bundt cake pan, a few clippings from nature (I got all of mine in my yard), and water.
Arrange the leaves/berries/apples/etc in the pan, so that you will have a little of everything showing on all sides. Don't forget that the bottom of your pan is what will actually be showing, so make sure you have some berries underneath as well.
Then just fill it with water and freeze!
Once it is solid, run warm water over the bottom of the cake pan while holding the ice wreath in, and it will slip right out.
Add a pretty ribbon and hang it outside! I hung mine on my mail box.