Im pretty sure thats incorrect, doesn't an extra one appear latter on in disk 2 or 3.
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whoops read that wrong, i thought he was talking about disk1.
As far as i know you can collect two of them from the farm, one on disk one and then one latter on. It's best to collect things as early as possible because alot of stuff will dissapear latter.
Go to gamefaq's and download the guide on items that can only be collected in parts of the game.