The 'cake box' is the small paper box in the photo, not a tin. It was traditionally sent home with a small piece of cake from the wedding...although it's possible grandma just brought the box home with no cake
I'm not sure how this was stored previously but I've had it in a small drawer in an old desk...no light but also no moisture control.
I'll check out the archival supply link next time on wifi...thank you paul
UV protective glass is something I'm not familiar with...would be useful for many things that I'm framing.
From what I learned about mounting pressed leaves and flowers from our hikes, linen and cotton cloth were acid free. I wonder, though, if water used to wash them could change the acidity?