Crows feet are valuable for anyone who works with the dead, either for summoning them, offering to them, or removing them.
Crow (and his larger cousin Raven) is known as a wise trickster, in some places accorded much the same status as Coyote and credited with stealing fire and delivering other boons for mankind.
Among saints, the crow or raven is associated with Saint Benedict, who was saved from poisoning by a raven he fed. He is also associated with the prophet Elijah, who was fed by the crows in the desert. Finally, he is directly associated with Saint Expedite, who famously trampled a crow (often pictured carrying a banner carrying the word 'cras', meaning tomorrow) as he embraced his faith on tbe spot holding aloft a cross that says 'hodie', meaning today.
I use crow feet as offerings to all three, as well as in amulets and mojo bags and in various works of necromancy.
Some left handed workers work with crows to send dark dreams or troubling spirits, to otherwise awaken engage a person's darkness, or to carry harm or death to a person.
It's no accident that a flock of crows is referred to as a "murder" of crows.
A note on sourcing: Although it is unlawful to harvest crow feet in the United States, these crow feet were ethically and legally sourced in the United Kingdom where there are no such restrictions, and imported into the US.