My Silence Knot is a term used a few times throughout Lemony Snicket's works.
The Phrase
In The Beatrice Letters, "My Silence Knot" is an anagram of Lemony Snicket, usually used in the form of an action. A perfect example would be "help me untie My Silence Knot and solve the mysteries of the Baudelaires." It is unknown whether or not "My Silence Knot" is a code for anything else.
The Sonnet
"My Silence Knot" is also a sonnet written by Beatrice Baudelaire, the object of Lemony Snicket's constant affections and the inspiration of his search into the Baudelaire siblings story. The sonnet was written as a part of a play that she performed while in school to train as a volunteer for V.F.D.. After it was written, it was put up for display in a glass case at the school, and later moved to a library. At the end of The Beatrice Letters, Lemony reveals that he found it in a warehouse filed under Beatrice's name. It is as follows.
My Silence Knot
My silence knot is tied up in my hair,
As if to keep love out of my eyes.
I cannot speak to one for whom I care.
A hatpin serves as part of my disguise.
In the play, my role is baticeer,
A word which here means "person who trains bats."
The audience may feel a prick of fear,
As if sharp pins were hidden in their hats.
My co-star lives on what we call a brae.
His solitude might not be just an act.
A piece of mail fails to arrive one day.
This poignant melodrama's based on fact.
The curtain falls just as the knot unties,
The silence broken by the one who dies.
The first mention of "My Silence Knot" was in "The Beatrice Letters" BB to LS #1. In this she states: "Now I must untie "My Silence Knot" and write to a man I have never seen..." This suggests that this is not the elder Beatrice because at one point she was engaged to Lemony, so it would seem that Beatrice Snicket adopted the using the phrase "My Silence Knot", just as she adopted words such as "baticeer".