I tried once a long time ago to stuff with rice and it works very nice, giving a great consistency to your creature. The only risk (but a big one) is that rice or seeds could over time turn bad and grow insects... yuck!
I read somewhere that if you put also inside the sutffing one of those little plastic bags with anti humidity (those you find inside the box when you buy electric equipment or cameras..) this should not happen but I never tried.
Probably, small plastic pellets are the safest way to go!
I have a book that's all about making beanie creatures
hey Hanabi, what book is that? Do you think it's available on amazon?