I have literally hundreds of earthworm casting mounds all over my lawn. I
know everyone says that is great for the lawn but it looks like crap! (no
pun intended)

What can I do to eliminate these?

I would think you could wash the mounds away with a garden hose.

If you really want to get rid of the worms, you probably need to replace the
grass and top layer of top soil with hard clay.

Dave
http://members.tripod.com/~VideoDave