Well:
-There's one in Peridot Ward, in a rock right next to a building. I don't remember the specific location, though... I think it was near the Pokemon Center? Not right by it, though.
-There's one in Obsidia Park, on the left side. I think it's hidden in a bush.
-There's one Under the Grand Stairway, but I don't know the exact location of it... I just know it's obtainable before Shelly, so Rock Smash isn't a requirement.
-There's one somewhere on... Route 1, specifically. Not either part of Aventurine Woods, definitely Route 1.
There's also one more... somewhere else (I think it's on Apophyll Beach), but I'm derping and I don't remember where it is. There are a lot hidden around Reborn, so it's hard to keep track of them all...