A'yup. Information and clues in the form of letters, telegrams, invitations, documents and page fragments: these added so much to our games over the years.
The HPLHS props available online, many of which are free, were a super source of mad inspiration.
The thing to keep in mind is that you can produce play aids in a manner that is fairly quick and painless, so your game keeping efforts are enhanced and not side tracked. Sure, you could spend a week or or even months creating the perfect Liber Ivonis, but a good show has more than just one prop; think about that.
Ideally, with a few hand writing type fonts and a little practice you can bring to the table, as often as is needed, play aids that put lost players back on track (never letting them know they were off-track!), that introduce new information or that move the story along. Ultimately these props create a scrap-book history of the history of the group's activity vs. the Mythos.
Everyone loves the mystery of opening a letter, or the excitement of a telegram requesting immediate response and the grime covered note found, damp with the morning dew, at the front door is always a treasured memory!
At least when we are playing Call of Cthulhu.