Do you need trees? This package has trees that you can use.

Look at the license on this product. LOOK at it. The author here clearly cares about the community, and it shows. The quality of these images in terms of DPI and resolution is great, and the artistic value of them means you should be able to find a use for each of them in your games or products.

Three images, provided as png for excellent scalability and quality. I love that the author has put such an open license on this artwork.