Take a range of things and pick whichever is most appropriate. Trust me on this. You don't want to be waving round a key ring that your DH made for you when he took a pottery class, and then discover that everyone else has brought "the results from the TSB test run" and "the sign off agreement for the Channel Tunnel project" because they forgot to tell you it's meant to be work-related.
Likewise if they all whip out their favourite teddies and you produce your GCSE certificate or something.
I suggest having something like the following options to hand (with a paragraph in mind that you can waffle about):
. Something small handmade by a child/partner/friend
. A good book
. A pen/phone/notebook- say something about being able to record ideas, inspiration, blah blah blah. If it all goes mega-serious you can claim the pen was the one you took to the very first project meeting you went to, and you keep it to remind you how much you've learned since then/ how you're still the same person you were then and sometimes need to get back to basics / something else vaguely appropriate.
All small, all things you could legitimately have in your bag at any time.
Or bring your knitting and at least you'll have something to do...
Or a bottle of gin and at least you'll have something to drink...
I mean, obviously you're right to say you're way too old for all this crap, but short of faking your own death, you're going to have to take part.