lavender in yard

Early summer night, a mysterous but familiar fragrance flying to me whenever I open the front door. Try very hard, I used to, knocking my deep memory. Even taking a long long breath, I still could not recalll what it was.
From time to time, that smell welcomes my guests. Once a while, that smell quietly says good bye to my friends. Day by day, that is purple lavender embracing our lovely little blue house......