It's toxic, I wouldn't risk it.

Here is a link that might be useful: http://thehauntedgardens.blogspot.com/2010/02/voodoo-lily.html

Are you sure it was A. konjac? I've never known them to be water or even marginal plants. A lot of plants get called "Voodoo Lillies", not just Amorphophallus. There's plenty of Aroids that are water plants and pretty well all Aroids are toxic. Even the edible ones need careful preparation. But generally fish that do nibble on plants pick up the toxicity and then avoid the plant. They say eating them is like eating glass shards, not a pleasant experience that you'd want to keep doing.

Maybe they were Sarracenia...pitcher plants?