So often clients say they can't grow anything because it's too shady, true for some plants but I grow almost everything in some kind of shade as I live in an old neighbourhood full of mature trees. In this photo, some of the best for deep shade, sweet woodruff in the foreground, cimicifuga, hosta, goats beard and ferns.
Solomons Seal, an undemanding perennial for any shady or moist spot, so named for the Star or David shaped flowers that hang off the underside in late spring. These are a nice batch in my neighbourhood, I have found that they mostly stay in place, not invasive like Lily of the Valley for example.
Goatsbeard, a large perennial for shade that blooms in white feathery plumes. There are many varieties and sizes, the one above is new to me, a thread leaf goatsbeard that is prohibitively expensive according to my better half so I'm not allowed to have one :(. I do have two of the large varieties though, in Calgary they grow about 4 feet tall or so, there are a few on my block that grow outstandingly on the north side of a house. They bloom in early summer and have beautiful foliage for the rest of the year.
Meadow Rue, since we don't easily grow maiden hair ferns in our area, how about a meadow rue!? The fine foliage reminds one of ferns except this perennial also blooms in fuzzy ball shaped clusters in shades of pink to lavender to red hues. There are a few varieties, some miniature and some quite tall, like around 2-3 feet.
Ostrich Ferns, probably the easiest and hardiest of the ferns to grow on the prairies. These ferns spread by underground rhizomes after a few years, so hopefully you'll end up with more than you planted! A ferns mortal enemy is hail storms, try to plant them in a sheltered location!
Rodgersia aesculifolia, is not supposed to be hardy in zone 3 but I've had these for several years in my shade garden! The rough and thick chestnut shaped leaves are occasionally topped by fragrant plumes of white flowers (unless a squirrel breaks them off). I seem to see them for sale, more and more these days so give them a try. I grow this in a very shady spot under giant lilacs, sometimes the intense July sun can burn the leaves so I put up a little shelter until we get cloudy days or that time of year passes in a few weeks. Mulch with plenty of leaves in the fall to help them get through the winter. They spread quite slowly in our area and are low maintenance once established, I've also seen them growing quite well against the north side of a house.
Annabelle Hydrangea, since hydrangeas like to be moist they prefer to grow in dappled or part shade on the prairies, they would resent too hot and dry a location. I've had these for many years, they grow quite happily near my house in the light shade of the Mountain Ash tree. There are lots of Pee Gee or panicle hydrangeas available now too, they seem to also like the same conditions here.