Ever dried flowers and herbs from your garden? Take a loose, small bundle of herbs or flowers - but don't make the bundle too thick. Air has to be able to flow through your herbs. Tie with a cotton string & hang it somewhere cool & dry.
Instead of a message book, buy a tonne of vintage keys with little tags on and people wrote on them and deposit their message about "the key to a happy marriage" Can make a garden ornament out of them and a print on notonthehighstreet from te messages.