Small native trees noted for their flowers
I don't think any of the trees in this list will grow over 50 feet, and many of them won't grow nearly that high. Their scientific names are listed as they appear in the USDA Plants Database (and the links lead there.)
Amalanchier -- Serviceberries, including Amelanchier canadensis (L.) Medik. (Canadian serviceberry), Amelanchier alnifolia (Nutt.) Nutt. ex M. Roem. (Saskatoon serviceberry), and Amelanchier arborea (Michx. f.) Fernald (common serviceberry).
Cercis canadensis L. -- Redbud (Judas tree)
Cornus florida L.-- Flowering dogwood
Crataegus L. -- Hawthorns of many sorts including Crataegus pedicellata Sarg. (Scarlet hawthorn), Crataegus crus-galli L. (Cockspur hawthorn), and Crataegus punctata Jacq. (Dotted hawthorn)
Hamamelis L. -- Witchhazels
Malus ioensis (Alph. Wood) Britton -- Prairie crabapple (and other American crabapples)
Prunus L. -- Plum and cherry family, many members including Prunus americana Marsh. (Wild plum), Prunus pensylvanica L. f. (Pin cherry, Fire cherry), and Prunus virginiana L. (Chokecherry)
Sorbus americana Marsh.. -- American mountain ash,
Viburnum L. -- Some of the tree viburnums are Viburnum dentatum L. var. dentatum (Southern arrowwood), Viburnum lentago L. (Nannyberry), and Viburnum prunifolium L. (Black haw).