The Breeder of my Beardie recommended Bran. Looks okay and is completely digestible. Only suitable for a youngster, though as it's not supportive enough for an adult. It's also cheap and easy to maintain - remove the soiled areas and replace with fresh.
1.0.0 Bearded Dragon/Killing Machine : Roddy
1.0.0 Crested Gecko : Merlin
0.1.0 Gargoyle Gecko : Amber
1.0.0 Yemen Chamelion : Bruno
0.1.0 Shrieking Cockatiel : Chip