I found japanese millet while looking for duck forage and fodder. It is highly recommended by duck hunters as a flooded food plot crop.
It is cheap for small applications ( the seed is very small, 1# = 155,000 seeds). I've raked back the top layer of muddy leaves in a nearby seasonal pool, hand broadcast the millet, then lightly distributed some of the leaves back over to discourage birds. It seems like a great option for seasonally flooded marginal areas, or in wet Swales and pond edges to provide both forage, nurse crop, cover, and grain.
Japanese Millet Seed - Japanese Millet Seed is commonly used for feeding ducks as this millet will grow in flooded soils or standing water. Japanese millet duck food plots should be planted before the rainy season allowing the plant to sprout and begin growing before the standing water comes in. This millet can handle standing water if the young plant doesn't become completely submerged. Japanese millet is most successful when planted on prepared soil, although Japanese millet will germinate and grow just about anywhere. For Duck food plots, plant the Japanese millet early in the summer (June-July) depending on the start date of your duck season. Japanese millet seed heads will hold on longer than most millet varieties, even in standing water. The seed will slowly drop out of the seed head feeding the ducks over time.
Japanese millet is well suited for areas with wet conditions. With a tolerance for wet and muddy soil conditions while growing, Japanese millet is able to be flooded while growing as long as its leaves remain above water. After maturity is reached, a Japanese millet plot is able to be flooded and used as a duck pond due to its tolerance for wetness. This tolerance for wetter conditions also makes Japanese millet a strong nurse crop to protect slower growing, more tender legumes.