Middle Primitive Elvish
salak
root. *grass
salakwē
noun. *grass
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.
The first iteration of this root was unglossed ᴱ√SḶKḶ in the Qenya Lexicon of the 1910s with derivatives like ᴱQ. salki “grass” and ᴱQ. silki- “mow, scythe, mow down” (QL/84). It also had derivatives in the contemporaneous Gnomish Lexicon such as G. salc “green cut grass, ensilage” and G. salca- “to scythe or mow” (GL/66). The root reappeared as extended ᴹ√SALÁK-(WĒ) in The Etymologies of the 1930s with derivatives like ᴹQ. salqe “grass” and N. salab “herb” (Ety/SALÁK).