Owlboy

There are 3 Golden disks to collect through the game. They can be easily missed, but you can go back to their areas whenever. Note that you can place the disks in some statues to unlock a new backstory, but this isn't needed for any trophy. If you do place one before collecting them all, this doesn't void the trophy.

First disk in the Owl Temple:



In the Owl Temple, you'll eventually reach an area with a little purple vine in the bottom right corner of the screen. This is a secret area, enter with Otus only, and proceed until you find the disk.


Second disk in Tropos/Strato:




In Tropos/Strato, fly up in the area where you saved one of the Boguin Brothers. Continue flying up the screen until you see an arrow sign with a vine on the left. Go to the left, burn that vine and follow the path until you reach a tree, the disk will be there.

Third disk in the final area of the game:




In the final area of the game, you'll eventually reach a kind of bolt in the space that you have to hit by standing on it to make it move. When you reach the top, you'll need to go left to proceed with the story, but you can also go to the right to collect the last disk. Follow the right path by jumping on the platforms until you reach the disk and collect it.

Note that the game will warn you before going to the final area that it's the point of no return, but it's not totally true. When you enter this area, you won't be able to go back before defeating the last boss and finishing the game, but then you'll be able to reload your save and you'll be in the area before the last boss and will be able to teleport yourself back to Vellie.

Here is a video that will show you how to collect them all: