Oxbow

This is an interesting landform.  Why do you suppose these farmers have arranged their fields in a horseshoe shape?  I think I know.  This area is just east of the Mississippi River, somewhere around Memphis.  The thing about rivers like the Mississippi is that over geological time, they meander.  That is, they create little loops on either side of the river when the flow of water erodes the bank.  It is hard to describe, so look up "Oxbow Lake" on Wikipedia.  Anyhow, I am guessing that the oxbow formed, and the river moved away, and then the land filled in.  This is in exactly the correct shape for an oxbow lake.