water chestnuts - Trapa natans

Please how growable and eatable are the seeds of water chestnuts? The floating rosette type rather than chinese water chestnuts (Eleochasris dulcis where you eat the corms) I believe they succeed to water domination in areas of the US?
I am looking around for ideas of small plants to grow in water butts that wont mind a bucket swishing past them periodically. I am going to play with floating lettuces etc in polystyrene too. I'm on a mission to utilise my water butts for multiple functions.

thanks

According to Plants for A Future, they have a high edibility rating. http://www.pfaf.org/user/Plant.aspx?LatinName=Trapa+natans

http://www.eattheweeds.com/water-chestnut-water-caltrop/