Thrum pum pum pum

 I DID finish knitting these "thrummed" mittens in time for our gift exchange New Year's Day.

Definition of THRUM

1a (1) :  a fringe of warp threads left on the loom after the cloth has been removed (2) :  one of these warp threads

b :  a tuft or short piece of rope yarn used in thrumming canvas —usually used in plural

c :  bit, particle

2:  a hair, fiber, or threadlike leaf on a plant; also :  a tuft or fringe of such structures

— thrum adjective

Origin of THRUM

Middle English, from Old English -thrum (in tungethrum ligament of the tongue); akin to Old High German drum fragment

First Known Use: 14th century

This shows what they look like inside.  TOASTY.  COZY.  WARM.  SOFT.

 My daughter in law who coaches outdoors in New England winters says they really help (and also while walking the dog).

The little heart shapes are just "accidents" of how the un-spun tufts get incorporated into the vvvvvv's of the knitting.