Thanks for hosting Belita. A really interesting theme and gives plenty food for thought. Also congratulations on the banner photo.
Here you have the contrast of the green stalks with the red peppers
I found quite a few contrasts in this photo of the sunset above where I live.
I found the berries of the Rowan tree contrast well with the leaves.
And I found this photo interesting, where the growing crops on the field contrast to the surrounding grass.