Puck was being told about a magical flower which could make a person fall in love with anyone while sleeping.
When I have the juice of that flower, I'll trickle some drops of it on Titania's eyes while she's sleeping. She will madly fall in love with the first thing she sees.
Puck then went to go find the magical flower.
Please give the flower to me. I know a place where wild thyme blooms and oxlips grow. It's covered over with luscious honeysuckle, sweet musk roses and sweetbrier.