I use biodegradable poop bags myself. The ones I use are made out of corn, I think.
I don't think you're encouraged to flush them tho'. But I guess you could do that... Never really thought about that, to be honest.

Anyway. I have no complaints about them. They work just like they're suppose to and they have a good black colour, so I don't have to see the ingredients while we walk to a garbage can

Best thing about biodegradable bags, is that you can "cheat" with a relatively good conscience. Say you're out walking and you have to pick up poop but there is no garbage can within miles. With these bags you can just discretely drop them behind a rock and in time nature will get rid of the evidence