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.
The silver-bell tree (Halesia tetraptera) is a much under used ornamental tree. A 1.5 m bare-root plant flowered in it's 2nd year of growth, and if pruned it could be grown as a large shrub. In flower they are quite elegant with all these small white, not silver, bell-shaped flowers in small clusters at each leaf. Our campus had quite a large handsome speciment, but new landscaping killed it by burying the roots to change the grade, exactly what the Phactor told them would happen when he saw what they were up to. Of course it took 3 years, and then the next year a new sapling was planted, but it will take 30-40 years to replace its predecessor. And any good arborist would have seen the problem if consulted, and it was in an arboretum too! That required a special form of incompetence. Although native to moist woodlands from west Virginia to southern Illinois, they seem quite hardy in zone 5 and fairly tolerant of our droughts once established. This is one of two members of the Storax family in our gardens; the other has been featured as a Friday Fabulous Flower, American snowbell.