Matriarchal societies in Tolkien's world? Perhaps not. But love stories about a lady of high birth and a poor but brave man (often dispossessed heir of a noble lineage, but not as noble as the lineage of his lady love) are extremely common both in Silmarillion and in LOTR.
Some obvious examples: Melian and Thingol; Luthien and Beren; Finduilas and Turin; Idril and Tuor; Arwen and Aragorn; Galadriel and Celeborn; Aredhel and Eol.
Actually, this is an archetypic situation for matriarchal societies when kingdoms are inherited by daughters or nephews of the king, and his own sons are exiled and must win their own kingdoms by their own deeds of valour and/or a marriage with a princess. Greek mythology is full of such stories!
I noticed a lot of the women are missing from the genealogy tables in the Sil as well. Only if the woman (or Elf maiden) played a significant role was she mentioned. Turgon's wife is not listed. Eńrwen is only listed because there was a need to show Galadriel's relation to Thingol.
What about the people of Haleth!
But that only lasted till she (Haleth) died didn't it? And then her brothers son(s) took over? Haven't read it for quite a while..
Tolkien world is full of love stories between a noble valiant man (or Elf, in the case of Elwe Thingollo!) and a lady of a higher birth and social standing. However, in some historical periods people viewed such unions with horror. I just discovered that Romans did not accept marriages and long monogamous marriage-like unions betwen a mistress and her slave or her ex-slave (a freedman). At the best, the two partners were separated and exiled, at the worst, they were both executed, and the man was burned alive! I just found a fascinating essay on that topic at http://members.aol.com/pilgrimjon/private/LEX/SLAVEMIST.html
[Edited on 7/11/2003 by Eryan]