All cotton weaving yarn, heavy string type carpet warp, probably old Mayville thread. This is of lot of pale antique blue and off-white thread - four full spools of blue, five full spools (and two partial spools) of white. The spools are about 4" tall.
These have been stored away for many years, and the outer wraps are very discolored and dusty. The thread is very strong and supple, though.