It's a key, Toto.
2 seconds sound clip from the Return to Oz movie soundboard.
You can hear this line at 00:04:07.333 in the Blu-ray version of the movie.
Quote context
[...]
- A shooting star, Toto. A shooting star.
- Did you lay an egg this morning, Billina? Let's go see. Where's your egg, Billina?
- Billina, if you don't start laying again, Aunt Em says she's gonna stew you up for supper.
- Aunt Em, look! A key from Oz!
- It's just a key to the old house before the tornado. I must've turned it a thousand times.
- No, look, Aunt Em. It's proof. 'O-Z.' Oz.
[...]