No. Don't lie. She already knows anyway.
It is humiliating to a wife if her (stupid) husband doesn't remember something (so important) like the day they were (supposedly happily) married.
I hope the groveling and the ideas that Joe Nation offered are on-going in the Bear household. If not, man, you'd better start!
I admit, knowing my own husband has a very poor memory, I, as a good wife, begin talking about where we're going to go early enough that he has PLENTY of time to come up with something worthy. But only because he had a lapse... still rued by him.
Every marriage needs at least one of these lapses, but you'd better make up for it with costly and time-consuming, thoughtful gifts. I'm not kidding.
Good Luck and Happy Anniversary.