What is wrong with silica gel?
Store them in a sealed plastic box with a lid clipped shut. I store my rolled oats (for porridge) in such a box.
Put some well-dried grain in to absorb water from any leaking air, in other words use this as a substitute for silica gel. The grain (wheat, oats, maise, rice) can be dried in an oven.
What is your local climate?
What is wrong with slica gel?