I was asked this question after my post on Cullen species,
https://toowoombaplants2008.blogspot.com/search?q=Cullen+tenax
None of my bushfood books mention it, but I found several internet references to recipes for using the seeds in cooking (a cake, and biscuits).
I could find no references to aboriginal use of it, or to any testing having been done to establish the safety of eating the seeds.
I am aware that enthusiasm for bushfoods has led to some experimentation with foods that may not be safe to eat, so would not suggest that anyone do it, without having some further knowledge.
Can anyone help us here?
