If you delete comments stating why your theories can't be true than I find this pretty hard to respect.
Reposting here:
Your theories about them "having to put odd mushroom somewhere as child" are simply not true. This is exemplified by your prediction that all adult trade items are somewhere as a kid and we just need to find them. They aren't - this can easily be verified with Utilities of Time. There are plenty of items that just don't appear as child or don't appear as adult. All the other adult trade items (as kid) are one example, Kokiri Sword (as adult) is another example.
Your idea about it being an accident is feasible, but only if "odd mush" and "heart piece" are stored in a similar way when in a chest. Someone can probably check the hex for this and see if odd mush in chest and heart piece in chest are a byte away or something. It is unlikely, but feasible.
The generally accepted answer is that the Odd Mush was originally intended to be obtained as child. We know a lot of things were changed throughout development - we don't know if the odd mush was even a trade item originally or if Gerudo Fortress was an adult area. Since they blocked the area off from child access, they didn't bother changing it later once the role of Odd Mush was changed (there is evidence of similar laziness in a lot of areas, especially with cutscenes). [You didn't remove this last paragaph, but I'm reposting here anyways]
Last edited 03 Nov 2011, 21:20 by RingRush.