Hoarding + using unused vintage USPS stamps

My late father-in-law made first-day covers for each new stamp issued by the USPS. One of his legacies is a trove of unused vintage stamps, and now a small joy for me is seeing which ones my mother-in-law uses whenever she sends us mail. Stamps never go bad and as long as you have the total value of the postage correct (currently $.82 for a 1 oz letter), you can layer an envelope with a small gallery of cool old stamps in all sorts of denominations.

Easy to find on eBay + Etsy!