Something to grown in the shade
Here's a photo of the area between the retaining wall and the yard border. The border consists of a bunch of wild trees.
Notice that there's a section of the area that there's no grass? Well this is because it's shaded by the tree. Because it's downhill and covered by the tree, it probably doesn't get that much water either. The soil is hard and cracking there.
What can I grown there? I rather stick with some sort of Illinois native plant, which rules out Ajuga and Sweet Woodruff. The latter I am actually very fond of but feel that it may take over the woodland.
My wife is fond of ferns, but one would think that wouldn't work since it wouldn't be wet enough.