Not much to say really. A cereal crop, which similar to wheat, oats, etc can be ground into flour and bread. Un-ground crop can even be cooked with water and eaten on its own. Not to mention eventually being usuable for distilling and brewing. Unlike the other cereal crops, rice would be farmed in the same manner reeds are. Seed-wise, not entirely sure. Perhaps foraging/botanizing marsh tiles. In terms of usefulness it would provide people with limited land (say islands) an alternative cereal crop. Very filling food with a number of nutritional benefits; however, I'll leave the food values to Devs for balance needs.