Thank You lovingmama, exactly what I was looking for.

I have only used rice but i have heard of people using buckwheat and corn and such. I would check and make sure the flannel is 100% cotton. you don't want it to catch fire or melt when it is heated up. a very very very bad thing.

I have used rice, flax seed, and have one with feed corn.
I use a 100% cotton fabric to make the bag, then I make a pretty "pillow case" cover for it. That way it can be washed easily if it gets soiled.
If you are concerned about bugs and such, simply put a bay leaf in with the rice, etc. I usually break my bay leaf into smaller pieces too.

Good idea about the bay leaf, I have put them on the pantry shelf to repel bugs. Does it give off a smell when heated?

We love our rice bags! Aches and pains, cramps, stiff shoulder, cold feet, you name it and our bags get used.

I've made several shapes. Squares about 8" work well for knees, rectangles work well for the back or feet. For neck ones, I sew channels into a longer, more narrow tube so that the rice doesn't end up all in one place.

If you use field corn, make sure you get cleaned corn (this has had the loose chaff and small pieces of dried cob) to reduce possibility of fire.

Using muslin, I make a bag the size desired, then make a pretty outer case; this makes it easier to keep clean. Your fabric is very pretty!

*The bay leaf smell is not too much. It does if you happen to get the bag wet!
Do get the feed corn from a feed store or a grange supply etc.
Bags can be made in all kinds of sizes~

I use dry corn. I get it at the feed store, or you can find it in the pet supplies, sold as squirrel feed. for me the corn holds the heat longer. I'm thinking it would be nice to some pillow case for the bags. it make easy to wash and can make some fun one for the kids. It is on my someday list.

Thank you all for the information. I got all the squares cut for the rag quilt this morning, not to get busy sewing.

I make mine in 3 sections to each section I add 1 cup of rice and 2 tbsp of pickling salt.

What does the pickling salt do?