The simple rental agreement is just paying a set fee for use of the land for one year. Most cash rents are paid half April 1st and the balance Oct or Nov 1st.
One major legal issue that is different state to state is on the continuing use of the land if not under a written contract. Here in Iowa the tenant has some pretty strong legal protection. Either party ( land lord or tenant) has to notify the other in writing before Sept. 1st. if they want to change the agreement for the next crop year.
Not many states have this. In those states you have to depend on having a iron clad contract to protect your self.