I just installed UE4 and started a new FPS map (with starter content). I started trying to set a texture for a landscape, but there is only one texture in my content browser (FirstPerson Crosshair) (content->FirstPersonBP->Textures)
is there a standard texture pack that I’m missing?
I don’t think you used the starter content properly … I have checked the textures folder under “StarterContent” and I have a shed load of textures.
As already mentioned, you surely forgot to include the starter content. 
You can find more textures in the free demos which you can find in the learn tab of your launcher