I am going to second the wine and parent’s night out gift certificate. The baby wont remember any toy, and it will become just part of the mess the parents have to deal with regularly. A night out or some nice wine - the parents will remember that and be very thankful.
When my daughter turned 1, I remember what someone at the party told me - the party was not for her, it was for us - for keeping her alive for a whole year! 
If you like the Parents, soft plushy toy animals.
If you dislike the parents…tambourines, slide whistles, harmonicas & toy drums.
{EVIL GRIN}
Drums.
Thanks for the ideas, everyone. I was a bit late posting the question and, to my shame, went with a literally-last-minute gift card to the toy boutique up the street. It’s a small mom-n-pop operation, so it should be nice for the parents to look around.
I love the Kleenex idea and will be doing that next time. 
God damn you, you beat me to it.
Maybe… but as the father of a 13 month old who’s working on Tooth #9 somewhere in his mouth, I’d say that a pound of some high-quality coffee would be every bit as welcome as an equally priced bottle of wine.