moonwort

noun2

1. •
   A small fern, Botrychium lunaria (lesser moonwort); later, any member of the genus.

   • Moonwort is an herb which they say will open locks, and unshoe such horses as tread upon it. — 1653
2. •
   (US, UK) Lunaria annua (greater moonwort); also known as honesty and annual honesty.