I have finally finished the little seed-stitch coat. In the end I chose to put a simple collar on it because there wasn't enough yarn left to knit a hood. I think it is probably better this way, we don't have much need for hoods in this warm climate anyway.
After sewing the coat together I looked at it for a while and decided that it needed something. A simple little trim to help define the edges, I thought. I looked through the yarn stash for coordinating colors and previewed their effect by laying a single or double strand of the yarn along the edge of the front band. The one I thought looked best was Lion Brand Homespun color 322 Baroque (that's a lovely shade of purple). One row of single crochet around all the edges did the trick. I even had matching buttons in my button stash.
I think this was a very successful stash-only project.