Vintage coin collection in black leather pouch

I lost a small black leather pouch that held a vintage coin collection that's really special to me. Yesterday around 3pm I realized it was missing after leaving the Market Street entrance to the Library Plaza in downtown Idaho Falls, East Idaho. The pouch is about 5x3 inches, pebble-grain black leather with a brass snap that’s a bit loose. Inside are three coins in clear sleeves: a 1909-S Lincoln cent, a worn 1921 Morgan silver dollar, and a 1943 steel cent; there’s a tiny red thread tied to the zipper pull as a unique clue. The pouch shows wear on the bottom corner and a faint coffee stain on the back. It’s a family keepsake from my grandfather, and I’d be incredibly grateful to get it back.