Below are the textures that create the unique Flatland landscape for the basic blockset. You can use these default textures anywhere in your spots by simply preceding the texture name with the "@" symbol and the name of the blockset, like so:
TEXTURE="@basic:cement.gif".

cement.gif	cherywd.gif	cheryw1.gif	clouds.gif	edgetop.gif
flatland.gif	floor.gif	grassground.gif	greenglow.gif	lamp.gif
loadtile.gif	logo.gif	metal.gif	metal3.gif	moon2.gif
stone.gif	sun.gif	terrain.gif	stonegrass.gif