What is it?

My yard continues to throw surprises my way. I've discovered crocuses, stemless tulips (they're old and tired), hyacinths, Easter lilies, hostas and mums. Plus some other flowers that I don't know the name of.

The most recent surprise is a small tree right outside the kitchen window. When we moved in last year it was full of oval shaped green leaves, nothing out of the ordinary. Then a few days ago something changed... it now has LOTS and LOTS of clumps of white flowers. They smell like a Lilac, look similar to one but according to my Dad who's the Master Gardener, they're not one.

Well, then, what is it? I must know! Any ideas?