FOUND IT!
My description was not very clear and accurate. You don't drive a tractor and it is viewed from above. This is much more fun than all other lawnmower games for the Amiga. Still not sure if this is PD or if it is a Commercial game? It has a publisher but if you judge by quality then this is PD.
Title:
Combine
Developer:
Zuidenveld
Publisher:
Video Computer Commercials
Year:
1989
Language:
English / Dutch
Link:
Download