After the game's opening cutscene, you'll end up next to your parked car. Walk down the nearly stairs and follow the path down to a tree covered in moss. Press the A button to clean it and unlock the Lost and Found achievement for finding the first memento. Keep following the path to a telescope, which you can examine to relive your first memory. Completing it earns you the A blast from the past achievement. Walk back towards your car for a cutscene, which will be interrupted by your phone ringing. You can answer however you like, and at the end of the scene you'll unlock Way back home for finishing the chapter.