This is what 100 bags looks like. These are mostly Kroger bags, with a few others thrown in. I collected these from friends, family, and recycling bins.

I sliced them into 1 1/4" strips with my rotary cutter, and filled this storage tub to overflowing. Sorry for the bad photo quality--my flash isn't working, and it was a cloudy day. I had to edit heavily just to get it to this point.

I meant to take a picture of the two balls of plarn I ended up with, but once again, no flash, cloudy skies. But I did have sunny skies on the day I reached the halfway point:

That's 50 bags' worth of plarn that I've crocheted, and 50 bags' worth still wound into a ball. This will be a messenger bag when completed. I'm thinking about using a thrifted woven belt as the strap, and lining it with recycled twill.