Oooo, TPP's yellow tree peonies are in flower, but maybe he doesn't want to over do the peony thing (but here and here anyways) . No problem; this time of year lots of things are in flower. At the back of our perennial garden is a spectacular young tree, a Carolina silverbell (Halesia carolina). This is a great ornamental tree, native to SE North America, but completely hardy in Zone 5. They flower when quite young and are tolerant of some shade. TPP has blogged about a different genus in the same family (Styrax americana - American snowbell). You get the idea, dangling white flowers are a thing in this family (Styracaceae - Storax family) and big bees love it. TPP also has a young Pterostyrax tree, but it hasn't flowered yet. Storax makes no sense as a common name because it's a reference to a medicinal resin from the appropriately named Liquidambar styraciflua (sweetgum) (note the specific epithet) which is in another family no matter which one this genus is now in. Seems there was some confusion way back when plant names were based on gum-resins. OK that's not your problem, but this is a highly recommended flowering tree.
Very few people in the midwest are familiar with this slender shrub even though Styrax americanus, American snowbell, occurs here in Lincolnland. Probably few people spend time hiking through wet woods or swamps of the southern tier where this shrub generally grows. It appears to grow quite well in less wet situations where it makes a nice, delicate addition to a shady border. My seedling has taken 5 years to reach a flowering size, but until this year it was growing in a very shady spot with very heavy soil, neither conducive to a good start. Flowering occurs in the late spring at about the same time as its better known relative the silverbell tree. Although the flowers are on the small side, even a small bush produces large numbers hanging below the branches.