evergreen shade plants and flowers
Look at our ornamental plant section on our website to get started. http://extension.umd.edu/hgic/plants/ornamental-plants
and Container Plants http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG600%20Container%20...
You did not mention the height and width of the plants or how large the containers are. You should check out some books on container gardening in the library.
Annuals - coleus , wax begonias, hypoestes, torenia, spikes, etc. Grasses- sedges, mondo grass, fiber optic grass; dicondra vine.
Evergreens (woody plants) - Osmanthus heterophyllus 'Goshiki'; low growing hollies
May be helpful to visit some nurseries and large garden centers for more ideas.
To overwinter woody plants outdoors - Plants in containers need to be 2 zones hardier than your zone. You may be able to place the container next to your house and cover with pine boughs or shredded leaves for winter protection. Or even better sink the container in the ground to protect the root zone from the cold temperatures.