Many trees and shrubs will grow happily in containers.
Here are a few suggestions: Acer circinatum (vine maple), Amelanchier, Bauhinia variegata (purple orchid tree), Cercis (redbud), Chionanthus (fringe tree), Cornus kousa (dogwood), Acacia, Stewartia, Bronze loquat, citrus, palms, Cassia leptophylla (gold medalion tree) and Hakes laurina (pincushion tree).
Each of these will provide spring or fall interest, and each will stay on the small side.