Seven Stars, Seven Stones and One White Tree...

[Snowdog]

Quenta Silmarillion 19, Of Beren and Lúthien
"And in answer he sang a song of challenge that he had made in praise of the Seven Stars, the Sickle of the Valar that Varda hung above the North as a sign for the fall of Morgoth."

It seems, with the exception of Mithalwen, that Groin Redbeard's quote has been either overlooked or ignored. The seven stars of the Sickle of Varda was in the night sky over the Northern Kingdom of Arnor. Though I'm not sure it's mentioned anywhere, I think it was a part of Arnor's banner, and Arwen made the seven stars a part of the united kingdom banner that Aragorn unfurled on the Corsair ship as he came upriver.