Listed amongst the "Must Have" Scenery Support Files" there are some commonly used textures, can't say I've used them myself but if thats what you're after there you go! Should be something of use in amongst that lot?
http://www.scenery.org/faq.htm

If not then perhaps you could download a few sceneries you think may have the sort of thing you're after & if you spy one you'd like to use drop an email to the creator & ask for permission to use it.