Alfalfa was widely used in Soil Bank and CRP, especially in the Western Dakotas, Oregon, WY and MT. Couple reasons, Alfalfa seed (variety not stated) was about the least expensive seed You could get. And those areas were and still are Honey producing areas. Alfalfa and Sweet Clover were almost always a part of the mix. And produced pheasants by the millions, and the CRP/Soil Bank NEVER required burning.
With this "ALL NATIVE" crap that goes on I wouldn't be surprised if Alfalfa and Sweet Clover are not allowed in new CRP plantings. I don't know? and would add them to the mix anyway. I hate Gov BS.
Most likely varies from area to area and the attitude of Gov officials.
Most all North American Alfalfa varieties were developed from Grimm Alfalfa. And Grimm is "All American" developed in MN from varieties brought in from the Middle East. Winter hardy, deep rooted and drought resistant.
Strong stems and tall, leafy and seedy.
Go to a Farmers Co op, get Alfalfa seed labeled Something like North West, or
Variety not stated. It will be a Heirloom, probably a mix of Vernal, Ranger and Grimm.
It is usually about 1/4 the cost of modern fine stem multi leaf varities.
If You buy the seed from a all organic type place, Alfalfa Sprouts etc it will get rather spendy.