An adjective tells which one, what kind, how many, or whose.
two- adjective (how many? two)
large- adjective (what kind? Large)
oaks- noun (Who or what is the sentence about? Oaks)
covered- verb (What did the subject do? Covered)
Your- adjective ( whose evergreens? Yours)
evergreens- noun (covered what? Evergreens)
There are three adjectives in that sentence.