A skein of yarn. The word skein is an abbreviation of an Old French word, escaigne, which referred to a hank of yarn that when folded back on itself resembles a 'v' shape.
The word skein is also used as a collective noun referring to a group of flying geese as they take on the shape of a 'v' in flight.
Another fun collective noun is a 'quilt of eiders', referring to a group of eider ducks. It was the feathers and down from these ducks that were used to fill eider downs, a form of padded bed topper and the fore runner of the modern day duvet.