I like to use seasonally tinted 御銘 for 濃茶, but here are some that are “pure” in that sense and that I like to use:
みよし野の 高嶺の桜 散りにけり
嵐もしろき 春のあけぼの
The cherry blossoms on Yoshino’s high peaks have fallen away;
even the wind that scattered them looks white in the spring dawn.
春すぎて 夏来にけらし白妙 の 衣干すてふ天 の香具山
Spring has gone, summer suddenly came. On Mount Kagu white clothes hanging to dry