Amelanchier canadensis (common name: serviceberry)
This is a really great small tree or multi-stemmed large shrub that provides 3-seasons of interest in the garden. Amelanchiers are incredibly low-maintenance; have pretty flowers and vivid fall color; plus they produce fruit reminiscent of blueberries in the summer. It is a mystery to me why this one is not used more often as a landscaping plant. We have three in our yard, and I love them.
Serviceberry is native to eastern North America, can be planted in full sun to part-shade, and will tolerate clay soils. They grow 20-30 ft. high with a 15-20 ft. spread. White flowers bloom in early spring before leaves appear (early-mid april for us here in N.C.).
Berries are really tasty.