The word ría “wreath, garland” appeared in the 1968 Shibboleth of Fëanor as a derivative of the root √RIG in a discussion of the etymology of the name Galadriel (PM/347). The same word ría “a wreath, garland” appeared in another 1968 discussion of her name, but there it was based on √RIƷ “wind about, wreathe” (NM/353).
Conceptual Development: In notes from 1959 Tolkien instead had Q. rië “garland” from √RIG “twine” (PE17/182). This in turn was a later iteration of ᴹQ. ríe “crown” from The Etymologies of the 1930s derived from primitive ᴹ✶rīgē under the root ᴹ√RIG having to do with crowns (Ety/RIG; EtyAC/RIG). As published in The Lost Road, this word was given rie (LR/383), but Carl Hostetter and Patrick Wynne corrected this to ríe in their Addenda and Corrigenda to the Etymologies (VT46/11).
The Qenya Lexicon of the 1910s had ᴱQ. serin (serind-) “wreath, crown” under the early root ᴱ√SERE “twine, tie, bind” (QL/83). In the contemporaneous Poetic and Mythological Words of Eldarissa it was Serin(do) “crown” (PME/83).
Neo-Quenya: For purposes of Neo-Quenya, I’d use the 1968 word ría for “wreathe, garland”, but I’d also retain 1959 rië for its 1930s sense “crown”.
ría noun "wreath" (PM:347)