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Please vote for interactive books where the pages hold removable items, such as letters, cards, photos, booklets, postcards, or small hard objects, such as the tiny magnifying glass included in The Jolly Pocket Postman. Books may not include "bonus" items, such as sets of crayons or stickers. The items must serve practical purposes to the stories' plots. Examples include titles in the The Jolly Postman series by Janet and Allan Ahlberg, and titles in the Letters From Felix series by Annette Langen.

Please only vote for interactive titles. Please don't vote for books written in an epistolary format, nor merely document pictures of letters, postcards, or the like. Books do not need to feature postal themes, but ideally should have full plots, despite some votes below manage to relate stories without plots. The Postman and Felix series happen to be the only books of which the list creator is aware that employ this form of interactive reading. Your votes could be for anything, fiction and non-fiction, as long as the title uses this type of physical format.

Also, please don't vote for any kind of interactive book besides those requested (so no pop-up books, touch-and-feel books, gamebooks ["Choose Your Own..."], coloring or doodling books, books that use stickers, and hidden object/seek-and-find books, unless they too feature removable cards, letters, booklets, etc. as part of the story's plot).

The only books of this kind appear to be children's picture books. However, if anyone out there knows of a book of this sort whose intended audience are adults and/or young adults, please don't hesitate to vote for it!