For starters, Edna's many, many responses when using items with, well, just about everything and everyone in the asylum, whether it's required for a puzzle or not. Harvey, Comic Book, and Police Badge are just the tip of the iceberg.
When she encounters an inmate in a bee suit she asks him why. He gives off a variety of complex reasons. Until Edna says...
Edna: Admit it, you lost a wager.
Beeman: I lost a wager.
When Edna tastes the Stinkydrink she starts sputter causing Harvey to worry, until she finally responds:
Edna: The natives have surrounded the fort, Colonel.
After finally getting the Master Key and accessing the backyard, Edna can look into a couple of trash cans right outside the door. Both are filled completely with nothing but Master Keys.