The three stars note, as seen in the flash forward
Five post-it notes appeared on the Mosaic Investigation wall as seen in Mark's flash forward.
Four of the notes had text written on it, and they were later recreated by Demetri Noh, following Mark's recalling of his flash. The text on each of the four notes was:
The fifth note had three stars drawn on it, and it was recreated by Mark himself, from his memory.
Together with the eight calendar sheets, the five post-it notes became the first objects on the recreated Mosaic Investigation wall.