I don't know that I have a favorite non-magical item.
I do however have a favorite collection of non-magical items.
Aurora's Whole Realms Catalog is something like those old Sears catalogs from the turn of the last century. It has all sorts of items, from a tree stand, to beers and spirits, cheese, bandages, pens... basically any common (and many uncommon) items that you would expect to find in a fantasy world. I've spent hours and hours flipping through this book, just soaking in the descriptions and pictures. It's well worth picking up if you find a copy.