Legacy Premium Muslin from Jo-Ann
It feels very nice - and it is tightly woven - I consider it to be a high musliln.
My experience:
I bought two 15 yard, 90-inch wide bolts of it. I think it gets stretched when it is put on the bolts and relaxes later. Anyway, both bolts were short about three inches from the full 15 yards.
I soaked 90 inch lengths in hot water (after serging the ends) and then rinsed them in cold water, and dried "until done."
Results:
The selvages looked "crinkly" when taken out of the dryer - but seem to stretch to the length of the fabric.
The width went from 91.25 to 91.00 inches.
The length (measured about three inches from the edge) went from 90 inches to 85 inches.