Or maybe the cloth had originally been a little heavier than sheet weight. You know, thinking about it the cloth part may have been a sheet, cut to set in the crochet strips. With the two strips about 6" each, that made the entire coverlet wide enough to be a bedspread/coverlet.

The crochet strips go the length of the spread, set in so when the spread is on the bed they are on top at the edge of each side of the mattress. Then there is a crochet edging around the edges.

I wish I had thought to take pictures when I was there last week!

I did some hunting online and here is a similar idea:




The ones my grandmother made did not have as much crochet as this or the same style, but the set in idea is the same.