Maybe I wasn't trying hard enough, because it seems I may have found the answer today, using just a few simple words in a Google search -- "Bates vintage jacquard bedspread". In particular, I was looking for that scalloped/wavy edge, which appeared to be finished with some type of serger stitch. I found one on Etsy, WITH a label!
Bates! I'm excited! There is nothing more irksome than having a mass-produced item that nobody can seem to identify. Bates was just a hunch, but a good one. I called the company, and they asked me to send pictures so one of their longtime employees could take a look. Should hear back early next week.
Some historical information from the Bates Mill Store website:
The Bates Manufacturing Company was established in Lewiston, Maine in 1850 by Benjamin Bates. It quickly became one of the largest textile manufacturers in New England and transformed Lewiston from a struggling agricultural town into a booming industrial city. By 1857, the Bates Mill in Lewiston ran 36,000 spindles, employed 1,000 hands, and annually turned out 5.7 million yards of the best quality cotton goods. Even after winning multiple achievements and awards for his textiles, including "Best Pantaloon Stuffs" and "Best Plain and Fancy Cotton Fabrics", Bates wanted more. Accordingly, in 1858 the Bates Manufacturing Company wove the first Bates Bedspread.
To read more about the Bates Manufacturing Company history, click here.
So, what do you think? Did I nail it? (can't wait to hear back from the company!) and by the way, I was so excited about the piece with the clue on Etsy, I bought it. :)