E: Found it. It's under textures\(tileset)Natural
It's a bunch of doodads smashed into one texture, so be careful if you plan to edit it.
Does anybody know where to find these? I need to retexture them due to them not really working with the autumn theme I'm working in, but the texture...
To be honest I'd rather spend an hour filling it with wheat, I was just wondering if there was a world editor function I'd been missing.
I think I'll just turn it into a building for the pathing and then turn it back into a unit after the deed's done so it can be walked through.