Contact an agricultural contractor to get the grass cut, round baled and wrapped. Then you just need to find a buyer for the bales of silage.... You will be faced with the bill for cutting, baling and wrapping though.
Alternatively, speak to a local livestock farmer and offer them a cut or two off your ground. Other than taking a cut or two of silage (round bales or clamp silage), someone might wish to make hay from your grass. If the land hasn't been fertilized with chemical fertilisers, it might be suitable for making hay for horses.
Depending upon your acreage, you might wish to rent the land on a cut only basis - the tenant would fertilise the ground and take several cuts of grass off it and give you a bit of a rental income. If the ground is rough and hasn't been cut/managed in a while, it might be harder to get someone to cut it for you.
