In Lord of the Rings, can quest cards with stars be used to pay for events that require you to discard other cards of a specific type?
Firstly I will point out there are two versions of the game: Fantasy Flight and the Original

Original Edition

The FAQ states: 


  Example: The Event cost at Speak Friend and Enter requires the players to discard a Friendship and Joker symbol. Frodo volunteers since he can discard any two white Hobbit cards to pay for the cost.


Frodo's ability is the same as a wildcard (or Joker as this edition calls them) and therefore I would say it is clearly correct in this edition to use a wildcard in this manner.

Fantasy Flight (Current)

The Rulebook states:


  Some cards have star symbols, which are wild. These
  may be played as any Activity symbol (Fighting,
  Friendship, Hiding, or Traveling). 


It doesn't give a specific example like the older edition but given the older edition allows the usage of wildcards for events it would seem logical that it is still allowed.