Meaning of dark-tressed, copper butter, silver sentinel

“On an autumn afternoon, your dark-tressed mother gave you life.”

What does “dark-tressed” mean?

“The sun was a stout ball of glowing blood. The stones of this farm were copper butter.”

What does “copper butter” mean here? That the stones are as red as copper?

“He thought she meant the moon, rising over the house on the other side, a silver sentinel, and she did.”

My dictionary says sentinel is “a person employed to watch for something to happen”.

In here, does “a silver sentinel” refer to the moon?

Thanks

Potter

Hi all potted out

dark-tressed => dark-haired

copper butter => I would understand this to be a reddish golden color

a silver sentinel => Yes, I’d say this refers to the moon

Amy