Disc it. Turn you sod into a seed bed.

Though clover will come up if you spread on the hard soil you are not going to get the best germination rate. Cultivate the ground with a disc (or rototiller), spread your seed with a spreader, and pack the seed bed back down with a roller or cultipacker. This will allow maximum seed to soil contact and your germination rate will be high.

Man if you got it in your head that clover plots cheap and easy, just wait. Some years it would be just as cheap to plant an annual. If this is going to be your first attempt at food plotting try to plant an annual. The bigger seeds makes it easier to get a first stand and will not be as frustrating.