For northern climates, damp soil, temporary flooding, ..... Alsike clover. It handles acidity and wetness better than white or red clovers.Soil PH still needs to be checked and adjusted with lime if neccessary. You may want to plant the alsike with winter Rye as a cover crop. Rye is cheap, handles poor soils. Winter Rye and Alsike are good, cheap, first year plantings in the north until soil quality is improved with lime and fertilizer. If theyflood out, you are not out much.