One of the most impressive security envelope sets on the internet is by Joseph King. This is a 166 pattern collection on Flickr. This page is the number one search result when you google “security envelope patterns” and has been for some time.
So I went through this collection and selected all the patterns that I do not currently have. These are all featured below. Think of this as my personal vision board.
If you recognize any of these patterns from your own personal or business mail… I want to hear from you! The more you have the better. If you send me your envelopes I will reimburse you for any shipping or postal charges.