Can't choose image I already have in folder

It would be brilliant if I could use an image that is already in a wp folder as the background image for a particular post. I sort of don’t want to upload 10 copies of the same image, just because that image works for 10 different posts.
Thanks! 😀

Other than that, plugin works well, image actually shows up, and if it doesn’t show up, then just edit the post and choose a different starting point (right in my case). I did try another plugin, but didn’t get that one working. Thankful for this one.