spoiler
In the first episode, Agatha tries to find out about the relevance of the book "Dialogue And Rhetoric Known History of Learning & Debate" by Andrew Ugo to the death of Jane Doe.
Of course, it turns out that the book name initials spell DARKHOLD and that Jane Doe is Agatha's visualization of Wanda's death.
But the name of that author, Andrew Ugo? It isnt stated in the show. Turns out it is an anagram of Wundagore.
It makes perfect sense because the Darkhold is a copy of the etched walls of Mount Wundagore.
Potentially there are still other easter eggs. For example, the raven sits on a letter of a sign when it is shown, which could tie in with something else?