I’m not 100% sure because that depends on the context but
The subject is “tucked in between these multiple folds”
I guess it meant “(something) tucked in between~”so “something” was left out in this sentence.
I’ll need the context for the full answer, paste the sentences before and after this if you can.
Reworded and simplified:
“I knew that there were tokens.”
The key to understanding this sentence is:
「tucked」は受け身です。
The subject of the sentence is "I".
Mike Cash