Okay going to sound dumb here... How do I do that?
Just go into the dungeon where you "go back in time to old Dragonspyre."
When you are in "the past," before you go out into the sunny plaza, stay in the hallway and turn to your right. Go all the way to the doors at the end of the hallway (you will not be able to go through them). Turn sharply left and walk straight into the corner. The stone rose is embedded directly into the wall.
I can't seem to collect the stone rose located in the dragon's roost. How do I get it? Thank you.
Unfortunately, you have to do nearly the entire instance in order to get this rose, up until the fight with Malistaire.
After you defeat the four soul servants, head to the left of your battle circle instead of going right up to Malistaire. The stone rose in embedded in the wall just in front of the crack in the floor that is cutting you off from where Malistaire is doing his ritual. It's kind of tucked away behind a rock so look thoroughly.