Other than Grim Discovery, is there any reasonable way to return lands from the graveyard in standard? The only way that I could see playing Realms Uncharted is with some way to return lands back to your hand. Sure it thins your deck out, but if you are playing Eldrazi spells I would think losing 4 mana would be a fairly steep price to pay.
The other two cards seem fairly good. My only issue with Ancient Stirrings is that, unless you have a way to shuffle your library, you won't be seeing the other four cards again.
Grim Discovery is fine for getting the lands back... Not sure how you reach the conclusion of losing 4 lands, seeing as two of them go to your hand. With Discovery, you get 3 of the 4.
As for shuffling, Fet ch Lands Say: "Hi!" . There are obviously many other ways, but those seem pretty much present in 99% of standard decks...
I didn't say you lose four lands, I said you lose four mana. If you are playing a deck with colorless Eldrazi cards than losing the Eye of Ugin and the Eldrazi Temple sets you back four mana. When I build an Eldrazi deck, I plan to have four Eldrazi Temples and one or two Eye of Ugins. When they all come out (via drawing them and expedition maps) you will effectively have 10 mana for colorless Eldrazi spells. Losing the Eye of Ugin and Eldrazi Temple bring you down to six mana for colorless Eldrazi. Therefore, you need an effective way to return the lands you would be forced to discard with Realms Uncharted. The creature lands are great, but I would rather like to play the Eldrazi which becomes more difficult if you lose the lands that make it easier to get them out.
I agree that the fetch lands would be an ok method of shuffling my library, but I would rather pop them when I get them and not wait until I get Ancient Stirrings to use them. I would need something that I can save until I get Ancient Stirrings without having too much of an issue.