Button Bush - can grow as a bush or a tree. Loves water. Friend of mine has one and it's doing great. For all zones. Fun plant.
Sara, it would help to know where you live and if you are looking for large trees, shrubs, etc. Button bush is a good choice for a native here is a link with photo, hardy from Zone 5 to 9, not all zones. http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/plant-finder/plant-details/kc/g830/cephalanthus-occidentalis.aspx
Photos of the site also might help folks offer more helpful advice for you.
Sara, yes, please tell us where you are and whether you are looking for something for sun or shade. When you say "help with water drainage," are you just looking for plants that will be happy in a wet situation?
I am Carol's friend that has the Button Bush. It is growing where I couldn't get anything else to grow--in a really wet corner. I bought it through mail order as a "stick" a few years ago and have trained it into a tree. It's probably 8 feet now, has these "sputnick" type blooms through the summer and doesn't seem to be bothered by anything--bugs or weather. It really solved my problem.
I live in Va, and looking to do something in the back yard, where we have alot of water that runs off into our backyard from the neighbors yard
In addition to the buttonbush, other shrubs that like moist to wet conditions include clethra, itea, red twig dogwoods, winterberry hollies and sambucus. Among trees, both pond cypress and bald cypress come immediately to mind, as well as dawn redwood and, of course, the willows.
Douglas recommends great choices, Itea virginica 'Henry's Garnet' has flowers in spring and great fall color, winterberry (deciduous hollies) have beautiful fruits in winter
itea...............is that to pland in poor drainage garden?
also podles of water in front yard, is sand a good filler
Itea virginica will take wet soils, I have seen it growing on the banks of a bald cypress swamp. Not sure I would plant in straight sand.
Nelly, these plants will take the wet conditions you have, but not change them. If you want to do that, you are going to have some drainage work done.
If you have a really bad situation and it is a low spot look up french drain.