I wouldn't invest a lot the 1st go around, swampy areas usually have poor soil, similar to a lake bed, unlike river drainage's and lowlands that often get extra from upstream. It may depend on what you term "swampy area", could be fertile as heck too. A grain rye with some arrow leaf clover may work for you..
You could buy a mixed bag like from http://www.mbsseed.com/
, or other regionally grown seed supplier. They have a small grain clover mix iirc at MBS. Vegetation and sunlight may be other limiting factors. In any case, be ready to at least use a rake to increase your seed/soil contact for better germination.