Are there any works composed (e.g., peoms, songs, short stories) in either Quenya or Sindarin by other authors than JRR Tolkien himself?
I am already aware of some dialogues in the Lord of the Rings films, these do not count here as an answer.
Pater Noster in Sindarin (JRRT for comparison)
NB: I am not competent to guarantee that any of these works are "correct" or "grammatical", with the exception of JRRT's submission.