Interesting use for commemorative. (These two came together, so I kept them as), maybe add to Christmas seal area collection.
(Found this one online)
Interesting varieties found on eBay
As of January 9, 2022, the fee for Certificate of mailing from form 3817 is $1.65. For mailings of more than three pieces you will need to complete USPS form 3665, listing all mail pieces in the mailing. You can use as many copies of the form, to include all the pieces in your mailing.