Hi,
First, I would amend your soil. Add some good compost, or a mixture of topsoil, sand and peat moss, so that the quality and texture of the soil is improved. This will help whatever you plant there.
I don't know where you live, so please check your your plant zone and that of any plants you may choose.
Now, on to the plants!
If you have the room, and if the plant zone is appropriate, one plant you might consider is the Hemlock. This is an evergreen tree that will take some shade. Along with those, you might also add some Rhododendron in groups. They are evergreen too, and would provide some flower color. The difference in plant textures would be very attractive.
