So that's what I've been working on. There's a good bit of yarn in the same bag that was holding the squares. I'm not sure what size hook I was using, but I seem to remember that it was my old worn size E, so that's what I've been using. It's a bit tight, but it will probably soften up with washing. I'm just adding a row of the cream and a row of the green, then assembling the row of 3 of these units as they are completed. I'm also working in the yarn tails as I go, so that there will be less of them to worry about at the end. At that stage I was cutting them pretty short, so they're a bit fiddly to bury, but I'm getting there.
Meanwhile I can start thinking about which set to tackle next. There are multiple possibilities.