Fewmets are the feces

Feces

Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...

 of a hunted animal, by which the hunter identifies it.

Fewmets is a Medieval English hunting term derived from the Old English, with the intimation that these droppings are the only hint of the animal's presence; that the creature itself has yet to be seen.

T.H. White's

T. H. White

Terence Hanbury White was an English author best known for his sequence of Arthurian novels, The Once and Future King, first published together in 1958.-Biography:...

 novel The Once and Future King

The Once and Future King

The Once and Future King is an Arthurian fantasy novel written by T. H. White. It was first published in 1958 and is mostly a composite of earlier works written in a period between 1938 and 1941....

makes reference to the "Beast Glatisant", or Questing Beast, constantly hunted by King Pellinore

Pellinore

King Pellinore is the king of Listenoise or of "the Isles" , according to the Arthurian legend. Son of King Pellam and brother of Kings Pelles and Alain, he is most famous for his endless hunt of the Questing Beast, which he is tracking when King Arthur first meets him...

 who uses its fewmets not only to track the beast, but to monitor its condition and state of health.
White describes how the Medieval huntmaster would wrap in leaves the spoor of the animal he was stalking, carrying this package stored in his hunting horn. This part of his job served two vital purposes:

Firstly, even if the noble sponsor of the hunt and his equally exalted guests were sufficiently skilled huntsmen to keep up with the hounds, it would have been beneath his dignity to dismount and examine the condition of the spoor

Spoor (animal)

Spoor is any sign of a creature. Spoor includes track, trail and droppings. Spoor is useful for discovering or surveying what types of animals live in an area, or in animal tracking.Generally droppings can be referred to as scat....

 to ascertain how close the hunted animal was. He would be shown the excrement, to ascertain from its condition how close the prey might be; but the physical task of retrieving the droppings would be left to the huntmaster—a skilled functionary, but also a commoner

Commoner

In British law, a commoner is someone who is neither the Sovereign nor a peer. Therefore, any member of the Royal Family who is not a peer, such as Prince Harry of Wales or Anne, Princess Royal, is a commoner, as is any member of a peer's family, including someone who holds only a courtesy title,...

.

Secondly, in the event that the patron was not knowledgable about woodcraft, the fewmets served as the huntmaster's bona fide. They were physical evidence that there was in fact an animal out there to be caught—and that the sponsor of the event and his noble friends were not being led in a merry and altogether pointless chase around the woods by a malicious or ignorant bumpkin.

In fantasy fiction and role playing games, fewmets are the droppings of dragon

Dragon

A dragon is a legendary creature, typically with serpentine or reptilian traits, that feature in the myths of many cultures. There are two distinct cultural traditions of dragons: the European dragon, derived from European folk traditions and ultimately related to Greek and Middle Eastern...

s or other mythical creatures. (Reference Madeleine L'Engle

Madeleine L'Engle

Madeleine L'Engle was an American writer best known for her young-adult fiction, particularly the Newbery Medal-winning A Wrinkle in Time and its sequels A Wind in the Door, A Swiftly Tilting Planet, Many Waters, and An Acceptable Time...

's A Wind in the Door, and others.) Dragon fewmets are often the source of gunpowder in such books and games, allowing black powder weapons into the fantasy genre.