Veggies to Plant along a Hawaiiian River?

Aloha from a lush wet site in Hawaii!

We want to plant an edible vegetable/herb (not fruit as we are already swimming in fruit:) ) garden and are trying to figure out what exactly to plant. About the spot:

It is along a space that becomes a river when it rains a lot. It will be a consistent river for 2-3 months out the year and runs off and on around the year when there is heavy rainfall. Sometimes where the garden would be floods so plants that can handle a day or a few days of being at least partially submerged would be ideal. It is almost completely shaded.

There are trees at all levels above so we prefer species that will stay lower to the ground.

Any advice would be greatly appreciated!

I would start out by looking locally, beginning at farmers' markets and such like. The various kinds of taro and also kangkong or water spinach (Ipomoea aquatica) come first to mind, but I doubt that either will thrive in full shade. You may have to look for or create sunnier niches. You might be able to create some stacks of logs, such that they are mostly above the reach of the floods, and grow mushrooms on these.

Wet combined with shade is a tough one. There are taros that will produce in shade, but the ones I'm growing in shade don't taste as good as the ones growing with more sun. Chinese cabbage and bok choy might work. Okinawan spinach might work. New Zealand spinach is worth a try. I think I'd also give kale a try.

I know that you said no fruit, but have you tried tree tomatoes? Cacao and plantains might work, especially the plantains.