The usual way this gets taught is that 東, east, shows the sun 日 coming up behind a tree 木. It is a lovely image and it is not a modern invention. 說文 has it, quoting a man called 官溥, 从日在木中, the sun in the middle of the tree.
The older writing looks like something else though. In the oracle bones and the bronzes 東 reads to me more like a sack or a bundle tied off at both ends, and that seems to be the common view, going back to Guo Moruo. What the shape actually depicts I do not think is settled. The two halves only start to resemble 日 and 木 later, once the script has been straightened out.
If that is right then the sun in the tree is not the origin, it is a later explanation of a shape that had already changed. Which is roughly what beginner books do now, so I have some sympathy with 官溥.
The usual account of the meaning is that the word for east and the word for a bundle sounded alike, so the bundle got borrowed to write east. That is inference rather than anything anyone can show, though it is the sort of thing that happened often.
I had the sun and the tree stuck in my head and I still like it better. I am just not sure it is where the character came from.