What do the children sing songs about in the first chapter of We Have Always Lived in the Castle?

The children see a song about poisoning to terrorize Merricat by recalling her family history.

The worst incident in Merricat’s life was the time her family sat down to dinner and it turned out to be the last meal for most of them.  The poisoning is common knowledge, as well as the reclusive nature of the remaining Blackwood family members.  Someone has to get groceries though, and that means that Merricat must venture into the world.

These trips make Merricat very nervous.  She does not like leaving the house, and being around people.  Almost no one is nice to her.  Everyone knows her family’s story, and they either harass her or look at her suspiciously.  Some people are crueler than others.  Even the children of the village seem to delight in torturing her.  Their favorite way seems to be a schoolyard chant.

Merricat, said Connie, would you like a cup of tea?

Oh no, said Merricat, you’ll poison me.

Merricat, said Connie, would you like to go to sleep?

Down in the boneyard ten feet deep! (Ch. 1)

Merricat tries to ignore them, pretending she does not understand.  She has several coping methods, most of them elaborate delusions and mind games, to get through these visits to town.  The children do not let her off easily though, and continue to taunt her by calling after her.  Their mother tells them not to call her names, but she laughs along with them.

The incident in town, including the children’s reaction to Merricat, demonstrates how isolated Merricat and her family has been since the incident.  Constance does not leave the house, and Uncle Julian can’t, so that leaves Merricat.  Every single member of the Blackwood family is mentally unstable and reclusive.  The entire village knows that the family was poisoned, and even though Constance was acquitted, they have convicted her in their minds.