Didn't even look for this crystal, very well hidden! I only found it because I could hear it (Hint!)
You know of all 4?
SPOILERS! DO NOT GO BEYOND
IF YOU WANT TO FIND THEM ON YOUR OWN!
*One is in a river out of your front door and right a little
*One is under the shield by the log out the back of your house, around the Golem.
*One is in the torch directly to the right of your door when going to the anvil.
*One is in the house almost directly out your front door and slightly to the right.
-Bringing all 4 back into that house and holding the Fear crystal has an easter egg :P