The crystals are;
1) in the river left of Ashtail where Crystalpaw is. Don't jump over just walk through and get the stone.
2) in the tree next to Alyssa. To get it talk to Alyssa.
3) In the elders' den with Liontail. You can wait until he dies or become leader and take it.
4) in the river all the way to the left
5) when apps, Nighthpaw will tell you that she found something cool and hid it in the apps' den. Night paw is right of the river.
Hope this helped!