I haven't tried any annuals, but between two tulip poplars in my yard, I have Virginia Bluebells (mertensia) and Epimedium blooming like crazy right now. They have spread each year since I've planted them. I also have Foamflower (tiarella), Japanese painted ferns (athyrium nipponicum pictum, and fern-leaf bleeding hearts (dicentra eximia)that do well, in addition to a number of small hostas. My checkered lily bulbs (fritillaria meleagris)look darling. I have a terrific clump of Lenten Rose (helleborus orientalis) but I hesitate to recommend it, since two knowledgeable horticulturists I know protest that there is no reason for it to do so well there. I also have a Magpie columbine (aquilegia) that struggles, but I love it just the same. Believe me, I've killed plenty of things I've tried there, so I understand your frustration. Whatever success I've had, I attribute to this: Digging deep and repeatedly to get rid of English Ivy that insisted on sneaking around for years, planting each plant with a generous pot-full of compost, and tossing some more on the bed whenever I get around to it, and keeping soaker hoses around the plants (but under mulch) to use during dry summer weeks. Good luck!

good ol impatens works for us