Hey, you're right about the Marignon gui thing! Dude, how dumb can I be?
To me it's obvious that the 'generic green' is foliage, but that may be because I saw it before making it a proper background texture
Anyway, you'll find at least a couple dozen free texture libraries with google, f. ex. with the keyword 'texture.' Most have nature photos as a category, among others. I'd wager glaciers and the like can be found similarly.