The Force Awakens has its own set of 15 Holocrons for you to find, each of which unlock a piece of general Star Wars Concept Art. Finally you can have a complete gallery.
Several of them are locked behind doors that can only be opened with a lightsaber, none of the three native characters can do that so you'll have to find a Champion Coin for a lightsaber user that you have to open them first.
Four of the holocrons can be found on Jakku's surface.
Star Wars Concept #29
Through a lightsaber door just before you have to smash a blockage in the "Sand Trap" mission.
Star Wars Concept #30
Shoot a target next to where you first see the town.
Star Wars Concept #26
A force door near Rey's AT-AT.
Star Wars Concept #25
A lightsaber door beneath the Salvage House. Near where you find Yoda's coin.
Space Above Jakku
Two can be found on the moon.
Star Wars Concept #17
On the surface of the moon, sitting on a rock next to where the blue pipe that goes through the deep gap crosses with a yellow pipe.
Star Wars Concept #24
On the surface of the moon, sitting on a rock next to a tall strut holding up a yellow pipe.
Another four are on Takodana's surface.
Star Wars Concept #22
Through a lightsaber door along the path to the right from the landing bay.
Star Wars Concept #28
On the rock directly in front of the castle.
Star Wars Concept #23
On the island on the far side of the lake.
Star Wars Concept #20
On a section jutting out over the water to the left of the castle, repair a ledge to reach.
Space Above Takodana
Yep, there's two on the moon.
Star Wars Concept #16
On a platform with a bounce pad, north west of the starting area.
Star Wars Concept #21
On a platform with oval holes in, south of the launch pads.
Replay the mission "Shield Shock" to be able to access these final three.
Star Wars Concept #27
Through a lightsaber door at the bottom of the elevator shaft section.
Star Wars Concept #18
Through a lightsaber door halfway up the elevator shaft section. Shoot two targets to extend a bridge.
Star Wars Concept #19
Through a lightsaber door at the top of the elevator shaft section.
For finding all 15 of the holocrons you earn the feat "History Lessons" and unlock "ME-8D9" for use as a Townsperson in your Toy Boxes.