craftgrrl | rice/corn pillows?

i work at jo-ann fabrics (in the education department, i love my job) and i was working at the register the other day. we're supposed to ask each guest what we're making (it usually comes up anyway) and a guest was telling me about doing corn pillows. i had heard about rice pillows, of course, but she was saying that she uses some kind of corn and that it works really well. she also said that she got a fifty pound bag for like $3.50 at a hardware store or something.

i was wondering, does anyone know specifically what kind of corn is used for this?

also, i was going to make some of these last year, but i bought some flannel and then noticed that it said "flamable! not suitable for children's sleep wear!" i since have realized that almost all fabrics say that, but i'm still curious what sort of fabrics work best for these, and are completely safe in the microwave? i've read that cottons work well because it can breathe, and won't rot. but yeah, are flannels ok? what about joann's "sew comfy" which is like a satiny flannelly fabric?