<unk>  is the common name of any of several plants with seed heads resembling a thimble.
Species called<unk>  include:
Rudbeckia laciniata
Anemone cylindrica
Anemone nemorosa
Anemone virginiana
Thimbleweed
Velvet grass
Canary grass
Tumble weed
Ryegrass
Pinworm
Flea
Ringworm