I've not handled one that's been done with beans/lentils. The downside is that those stuffings are relatively large, and the cloth doll is quite small by comparison, so you'll have a rather lumpy dolly.
Wheat bran can be documented as a doll stuffing, though, if that's cheap and available to you. Many of the leather-body dolls have bran-stuffed arms, legs, and bodies; with cloth dolls, if the bran gets damp, it can stain through the cloth a bit. Otherwise, stuffing with cotton, wool, or sawdust will be fairly common.