Thanks to Mary McCarthy of the Here-Be-Tatters list, the doily from my last post has been identified.
The doily is from Coats and Clark Book No. 317: Laces to Knit, Crochet and Tat. Mary uploaded the back cover of the book, showing the doily, to the HBT photos section, accessible to list members.
The next question is where have I seen this doily before? I don't own the book myself, but I am certain I have seen it. Maybe it was on somebody else's blog. I'll probably never know for sure.
Now, having taken this from Klara and John's house, I'm going to tat something else for their new quarters in the assisted living facility. I know what colors I'm going to use, to match the upholstery on the loveseat they're taking with them. I haven't decided on a pattern yet. I know it will have to be smaller than this one, but I can't decide on what I want to make.