The birds also like to play with it. Other animal bedding materials can be used. Crushed corn cob and pine shaving are a couple. I would not recommend aromatic cedar shaving. Some of these may make a big mess depending on your cage style.
Toys are a welcome treat.
Your birds are living in a one room house. Give them something to do. Finches don t play with toys as much as parakeets and parrots, but still are curious and like to put their beak into things. A sturdy string of beads hanging the from the top, a plastic ball on the floor, etc. Try different things.