In Greymoor from the Halfway Home bench you can easily farm rosary beads. Just head right out the door, and kill the six mobs. At the other end is a rosary stringing machine if you want to store them.

Run back to the bench and sit to respawn the mobs.

You can get 48 beads per run. It's not a ton, but it's consistent.

If you come here before you beat Moorwing, you can double your speed by using the bench next to Shakra, running back and forth.