I dont know about you but I love tucking little surprises into envelopes. And they are especially sweet if the envelopes are handmade and hand-decorated. Here is a video by joie de fi with several different styles.
And a “short” by The Colour Pad on making a simple envelope from a square book page.
Want to give it a try? I have packets of 20 pre-cut 6×6 and 5×5 pages from an old encyclopedia here on my Shop page, or you can buy them from my Etsy shop.