In this modern age where correspondence most often consists of emails and abbreviated texts, a handwritten note is twice as charming. And for the less technically inclined (my sister once pleaded with me, "Don't text mom. It takes her forever to even begin to respond"), it's doubly appreciated.
Assorted Dog Card Set, $18 via Rifle Paper Co
Spider Flower Thank You, $5 via Eggpress
Brass Parrot Letter Opener, $16 via High Street Market
"Flapper" Rubber Address Stamp, $22 via Paperwink
Wood Mail Desk Organizer, $64 via Less and More on Etsy
(Images: as linked above)