Old Money
This person found the object that they needed identifying on a demolition site, of all places. They were also found with another, more identifiable item: old money. These weird fabric items were found with money because they have monetary value! More specifically, the image shows 25 Mark notes.
While this isn’t actually money, they can be exchanged for money by retailers. To get even more detailed, the person answering this question included that they were linen and made in 1921 by the bank of Bielefeld.