I don’t know about you, but I love tucking little surprises into envelopes. They are especially sweet if the envelopes are handmade and hand-decorated. Old book pages are the best for these types of DIY projects. 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 available for sale at my Etsy shop.