Pink skullcap, Georgia Blue Speedwell, lemon thyme, and if you have enough sun, blackfoot daisy and four nerve daisy.

Salad burnet can last for a short time to years. They even tolerated the overhung-by-the-roof northern wall of our house. They kinda look like ferns most of the time, about 12 inches tall, but don't need as much water. They -do- need some water in the summer. They will put up bloom spikes of tiny, weird flowers in the summer, though, and some people cut those off so the plants remain tidy in shape.

Rain lilies never get over 6" tall and look great as a border bloom. I am not sure if the spider plant will live past your winters. Cone flowers do get to be over a foot tall and they come in many colors and seem to be hardy as far north as Illinois.

The cobalt blue flowers of Dwarf blue plumbago used in that capacity works very nicely for me. Here in San Antonio it's evergreen and the foliage turns an interesting reddish color in the winter. It blooms all season and I love the way it meanders among other plants or is perfectly beautiful just by itself.

Here is a link that might be useful: More about Dwarf plumbago via Google search

I'm with roselee on the dwarf plumbago. Here in Dallas it is semi evergreen to complete dieback (but it returns) in winter. I have it planted in one area with the large leaf purple oxalis and it look great together. I also like perennial candytuft, which is evergreen here and blue eyed grass "Suwanee" and pigeonberry.

You might try this sedum. I got some from a neighbor and it takes sun or shade: moist or dry. Needs sun to bloom, otherwise it is more green. I have it under a red Japanese Maple now.

Got it from a neighbor. Had mine for at least 7 years

Here is a link that might be useful: Sedum-kamschaticum

Have blackfoot daisy but mine jumps over the flower beds and just spreads all over. The four nerve daisy is my fave because of its neat habit and long blooming time, year round here.Prefers sun though,have not tried in shade.

I would love to add ruellia to the list. I have an north-east front yard as well. And had a few small pink ruellias that got eaten by deer, frozen to the ground and they always come back. This year with all the rain they have become low mound with beautiful bouquet of flowers each morning.
A bit invasive I would say, as it tends to multiply in the flower bed, and pops up a few feet away as well but not on the lawn.

Really, Florentino? I planted 8 blackfoot daisies this spring and they spread a bit more than expected (hanging over the sidewalk a bit) but I didn't think that they'd throw seed and spread readily that way. They did REALLY well this summer, even though I was bad and didn't water them regularly, they're acting as if they're established (and have been since June/July when they were planted April/May!) they did get supplemental water when the (established) plants in the yard said they needed it. Do I need to worry about next year?

I also like the dwarf ruellia, they've done really well in "exceedingly far north" Dallas, but I haven't had it spread like Pebble has....but then, I don't water the yard very often. It has spread in spots where it gets enough water OR in the pots I've had it in. And it's pretty drought tolerant. I don't think it would be difficult to keep under control.