To point out why USPS took note of them, there are unofficial Postcrossing tracking IDs recording nearly half a million postcards actively in transit from sender to receiver as of when I pulled that from their website a couple minutes ago.

Since the non-postcrossing Global Forevers are circular and a bit annoying, I use 2 Forever stamps plus a 20¢ stamp (6¢ wasted - i suppose i could switch to 15¢ stamps...).

18 U.S.C. § 501. If you post high-resolution, printable images of valid stamps, especially unused ones, and they can be reproduced, prosecutors could argue you’re facilitating counterfeiting.