Google Now continues to add more features to its cards, the latest being Stories from your Google Photos. The stories are auto-generated by having the Auto Awesome feature turned on in photos with your location history as well. If you go on a trip, vacation, hike, etc. where you take lots of photos, Google photos will automatically put them into a “story” where you can see a slideshow of your photos from your recent adventure.
So now rather than having to go to your photo album to see your stories, the most recent one will show up in your Google Now cards.