If you're gonna do that you might wanna move these unused/beta items into your beta rom. - All of these are in the debug rom.
Reed Whistle
The Reed Whistle was an item in an early version of Ocarina of Time. It allowed you to call your horse, similar to the Horse Call item in Twilight Princess. It was removed in favor of using Epona's Song.
Early Medallion
This early medallion is hexagonal, and has a different color choice. It doesn't look very good, so the developers decided to replace it with a better design.
Musical Note
Judging from one early screenshot, this was supposed to hover over Link's head when you learned a new song, much like when you get a new item. It may have been a part of a different melody acquiring system entirely. It was removed in favor of the dorky stance Link currently makes when he learns a new song.
Coin
No idea at all. Coins don't normally appear in the Zelda universe. And this one even comes in four possible colors.
Interestingly, the color-coding matches that of Rupees- green, blue, red, and gold/huge Rupees are covered. Perhaps a placeholder graphic?
Butterfly Cage
Now this is quite interesting. Apparently, you were meant to catch the butterflies that roam Hyrule. The question is what purpose they would have served.
Just to point this stuff out...
Btw this reply to you is my first post on this forum!!!!!!!!!!! ^.^