Hi Godfrey,
How are you? When would like to shoot the wheat fields, which season?
For your interest please see here previous requests for wheat field locations that might interest:
https://www.thelocationguide.com/forums/search/wheat+fields/
For USA and Canada wheat fields I suggest you contact Film Commissions in those countries by using The Location Guide directory that can be found on the main menu on this page.
I hope to see you at FOCUS 2019 ‘the meeting place for international production’ http://www.tlgfocus.com
With every good wish,
Murray