We buy a pretty (but inexpensive) bouquet of flowers or flowering plant at Trader Joes and I put it on her nightstand while she is sleeping along with a special birthday letter that I write reflecting on who she is and ways that she has grown/achievements over the past year as well as hopes for the year ahead. We usually make a special breakfast of the child's choosing. Note in the lunchbox along with (maybe) a special small treat or a special lunch (think a package of $6 grocery store sushi). Maybe leave her a little tiara in the morning that she can wear throughout the day to attract special birthday recognition/attention.
Mama to my three:
DD 2/2003
DD 5/2006
DS 3/2010