Yield Editor and FarmWorks View (also AFS View) are the free programs I have some experience with. I haven't looked to see if the FarmWorks one can still be downloaded. Kind of doubt it since the whole FarmWorks thing was taken down. Looks like AFS view can still be downloaded though.

AFS View
http://www.ctndata.com/download/AFS/v2017/2017.05.00/AFS_View_2017.05.00.exe


Yield Editor
https://www.ars.usda.gov/research/software/download/?softwareid=370