I don't really celebrate Earth Day by doing anything special. In my mind I think I celebrate the earth every day that I'm able to walk around and enjoy the outdoors. As a compulsive gardener though I can say one again I've splurged or didn't know when to stop and gone ahead and bought $800 worth of plants from almost a dozen nurseries that sell native plants.
Oxydendrum arboreum, is probably going to end up being the prettiest tree I'll have planted. They produce bell shaped flowers that aren't entirely showy but they're arranged like exploding fireworks scattered throughout the tree. In the autumn time these seed pods occur in the same locations and the red foliate makes them pop out even more.
Tilia americana, also has red foliage in the fall time, which is pretty but they lack the seed pods of the Sourwood. Their flowers are slightly noticeable as a pale yellow or blond color. Bees really love them.
Nyssa sylvatica, is another red leaf tree in the Autumn. The flowers aren't showy in that they're green balls of blooms, but bees absolutely love them and they go on to produce tiny blue berries that birds love.