Middle Primitive Elvish
m(b)er
root. *feast, festive
ed(er)
root. open
er
root. one, only, be alone, deprived
galan
root. bright
neter
root. nine
pantā
adjective. open
sī̆/sē̆
pronoun. she
tay
root. extend, make long(er), stretch
There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
A deleted root in The Etymologies of the 1930s with the gloss “open” and the forms √ED and extended √EDÉR, but it had no derivatives (EtyAC/ED).