In Hereditary (2018), I noticed Joan and Annie's children have mats with their names sewed on them.
Why do Joan and Annie's children have their names sewed on mats?
Movies & TV Stack Exchange is a question and answer site for movie and TV enthusiasts. It only takes a minute to sign up.Sign up to join this community
The door mats were made by Annie's mother, Leigh, . Those who are part of the ritual have a mat on their name.
The only key point is that Joan's mat has been made because she is willfully part of the entire ritual of bringing back Paimon.
Annie and her kids have been forced as part of the ritual and hence the doormats on their names.
Short Answer: The Doormats with names are markers for the Paimon ritual.
Hereditary is all about facing a destiny you can't escape from, and in that context I would say that: given that Charlie and Peter will be the next generation in charge of continuing to worship the cult, it's very likely that the grandmother would have prepared every single detail for this event, including the weird mats with their names on them.
In the case of Joan, it is pretty obvious that the mat is one of the proofs of her partaking in the cult.