I contacted the Star K about using flax seed for Passover. I was sent the following response:
The following grains (whole grains only) may be used on Passover. Purchase from manufacturers that do not process chometz grains. Consumers are required to carefully check grains BEFORE PESACH for extraneous
Does anyone know of any companies that process flax seeds that are not processed in the same facility as chometz grains (this knocks out Bob's Red Mill, Arrowhead Mills, and Nature's Path flax seed)?