I've wondered the same thing. I don't know where any markets are around here, so I went to Michaels the craft store and bought a few lotus pods w/ seeds in them. I have three little lotus plants growing from those seeds! It's definitely taking a while, but it worked! Good luck
Brian

Around here some of the farm ponds are chocked with the american lotus. I have read that the Indians ate them but I don't know of anybody locally eating them. I've never tried them myself yet have allway intended to. It seems the harvest would be something that would take some planning. You'ld have to wade out into the muck and grub them out. There is a local root buying station that buys the roots, I don't know who they resell them to though