I started a space page with some background photos that you can use to decorate profiles. The pics are open source and can be used for profiles.
SJ's Trees and plants backgrounds
I plan to add more photos over time. I set the privacy to open so that if you see a photo along the same theme, please feel free to upload it to the space.
I hope that some may find it useful.
If you add one of these photos to a profile, be sure to leave a comment on the space page.