For my orders, I have used only recycled cardboard boxes and envelopes and I use recycled newspaper to fill them in provide padding. I have heard about those biodegradable packing peanuts and they are interesting. The main concern I have with them is that they more than likely come from GMO corn which requires tons and tons of petroleum, chemicals, and gene splicing to create. In my opinion, genetic engineering and the steps that are taken to grow such crops is just as bad for our planet as drilling oil. Perhaps there are some non-GMO packing peanuts available.. but they would probably be rather expensive.
To me, it seems best that we use what we already have on this planet instead of creating anything new even if it isn't biodegradable. If an object is already here, then there's no turning back and I want to make the best of it. So I feel like it's great to repurpose bubble wrap and packing materials from other businesses. First reduce. Then Reuse. And if those don't work, buy new but be as sustainable as one can be.