Unfortunately, the most important element is road sand from Nova Scotia, handed off from a friend many years ago now - I am starting to run low and I don't know what I'll do for a replacement! 😅 Then I have some patches of Woodland Scenics fine ballast (mostly brown with just a pinch of gray) and Army Painter tufts (mostly "winter" variety but with a few brighter green or brown and yellow ones mixed in).