I was going to suggest 50 cents per day per cow/calf pair is a starting point - agmantoo is ahead of me with good advise today.
Would be less if you don't supply much, would be that much if you supply good fence, water, perhaps some supervision. So you are likely looking at less?
Watch out that folks don't over-stock if you rent by the acre. Different rainfall patterns mean more or less critters per year, in dry years you will get too many cattle on your land & damage the grass, take years to control weeds & get good grass back. They can put double the cattle on it, eat everything black, & move on.
A good agreement on who supplies what, what the stocking rate is: a good starting point is an extension agent in that area, might have example rental forums & what is customary in that area for rent.
Get a grip on liability insurance, as land owner you can be named in lawsuits by the renter or by the damage his cattle cause others. Often not your fault but you can still be dragged to court for it anyways, have the proper insurance.
Most folks are good, just mentioning the bad as well - you have to be prepared.
--->Paul