I very strongly recommend bark rather than stones.
The gaps between the stones quickly fill with dust and dirt and weeds grow like crazy. It looks great for the first season but becomes an undiggable weed fest afterwards.
With bark, you just buy another few bags of it and tip them out over the old bark.
Plus the bark mulches and feeds your plants.
As for planting, there are a lot of native compact grasses and low shrubs that prefer shaded areas, they will do well and look great.
TL;DR: avoid stones lest you never usage a spade in that garden again.