Hi Ann - Here are a couple of stitch patterns. They have some similarities. Hopefully someone will come along and will know for sure what that stitch is. Those towels are lovely, are you thinking of making some hand towels?
I think this may be your stitch! We just had a post on the site and they asked a question about this stitch Honeycomb Brioche I couldn’t believe my eyes; does it look like the same stitch to you?