I like to keep pretty envelopes or parts of pretty envelopes in my journal/day book, and I almost always keep the stamps. But the plain envelopes usually go in the recycling bin.
This time, instead of getting rid of the plain envelopes, I turned them into useful pockets for my day book! A pair of scissors and some pretty duct tape and washi tape did the trick.
And here are some of them in action:
Thank you to @bluebird for the pretty ephemera in and by one of the pockets 
The pockets are very pretty!