You would really need to give us more details about the topic of the poem or even just the Y line for us to be helpful but I can list a few words that start with Y for you:
YACHT
YACK
YAHOO
YAM
YANK
YAPPY
YARD
YARDLAND
YARDSTICK
YARN
YAWL
YAWN
YEAST
YELLOW
YELP
YES
YIELD
YODEL
YOLK
YOU
YUMMY
You would really need to give us more details about the topic of the poem or even just the Y line for us to be helpful but I can list a few words that start with Y for you:
YACHT
YACK
YAHOO
YAM
YANK
YAPPY
YARD
YARDLAND
YARDSTICK
YARN
YAWL
YAWN
YEAST
YELLOW
YELP
YES
YIELD
YODEL
YOLK
YOU
YUMMY