Reachfolk don't really worship Hagravens, some clans revere them for the knowledge and power they possess and some clans venerate Hagravens in order to learn they're nature magic. But just like the Reachmen and the Great Spirits, its more of a transactional relationship the Reachfolk have with the Hagravens.

Hagravens seem to be the Intermediates between the Reachmen and the Daedric princes, since they seem to have a stronger connection to Princes like Hircine, Namira, or Nocturnal and seem to be bestowed knowledge and power from those Princes. For example, Hagravens seem to be the only ones that are capable of preforming the ritual to create Briarhearts.

Still come clans actually revile Hagravens or at least very wary with there dealing with them, seeing them more as a being that can grant great power but at a price. These Reachfolk usually only deal with Hagravens as a last resort.