So, the Miskatonic pennant. One group of folks love it- the ones that didn't have their package crushed flat during shipping. The ones receiving mailers that did get stomped on the way through the post aren't nearly as happy. Their pennants are arriving with sharp creases, which is exactly the kind of problem I was trying to avoid by wrapping the banners around the flatpacked items.
Obviously, that approach didn't work.
There are two possible fixes for the problem. The first is to flatten out the creases using an iron set on low heat. Place the banner face down on a flat surface, place a sheet of paper on top of it, and then apply the iron. Based on my tests that should fix any mild creasing.
The second approach should work for even heavily creased pennants. This involves rolling up the pennant and immersing it in slightly warm water. Let the felt sit in the water for a few seconds so that it gets fully saturated and the fibers relax. Then spread it out flat on a horizontal surface and let it air dry. There may be some slight curling of the edges as the felt dries, but that's easily fixed with an iron. If you want your pennant stiff enough to display horizontally on the wall just apply spray starch to the back and iron on low heat.
Again, I apologize to anyone who had their pennant mangled in the mail. In the future I'll be using a hard-shell mailer for goods like this.