In the past when I have made rice socks I have used white rice. I am wondering if other fillers such as corn, buckwheat, flax seeds, brown rice, etc would hold heat better, or does it make a difference? I want to make at least one, maybe 2, for when I am in labor. I have loved the smell of them after they are heated ever since I was a child. Do you know if the smell differs if you use a different filling, even if it is just white vs brown rice?