normal files: green
block devices: yellow
broken links: white on red flashing
your ls command is probably aliased to something such as "ls -F --color=auto" if you only want it to be black and white remove this alias from /etc/profile.d/color_ls.sh or wherever it is. no real need to, it's handy having things colored.
btw. anyone know what black on dark yellow means? some of my little games are like that, not seen it before