mystery gifts...

I got a box from Amazon a couple of days ago. It was on the porch when I got home from work and I thought surely, as broke as I am, I didn't order something and forget I ordered it...but I had my doubts (it's happened before!). I snatched up the package and ran in the door lest the husband see me with a package during a time of such dismal fiscals.

I opened it and there were two books from my wish list from a person in Sacramento. I didn't recognize the sender's name (I write that with fear; should I know this person?) and no message was included.

I wasn't really sure what to do. I think I will send a thank-you note to this person for the generous gift (one was a creative fabric book and the other was a memoir called Running with Scissors), but should I do something else? Is there etiquette for mystery gifts?

It's much like I got invited to a exclusive dinner party where there are too many forks. The food looks delicious but I don't know how to properly eat it.

Any thoughts?

p.s. If the person is a blogreader and is reading this, THANK YOU! I don't know what prompted such a gift, but it sure was a wonderful surprise. :-)