What do you call it?

hah, it comes to the market today. 5 RMB yuan per KG, though very small yet.

I like eating it without cooking, a little bitter, but can feel the fresh scent of the lake. My mom said that when I was a very little one, I ever went with grandpa to lake on the small boat to pick up them. I did not remember it, but should be very happy hah.

Besides good taste, it can help one lose weight, and anti cancer.

I don't find the english name of it in the dictionary. It belongs to Trapaceae.