What's a good way to thank my coworkers for the baby gifts they gave me?

I work in a small law firm (3 lawyers, 3 secretaries including me and a bookkeeper). Yesterday the girls surprised me with a little baby shower in the conference room. They all went in and bought some outfits and stuff and one girl's mother even handmade a blanket. It was so nice!!

I know the normal thing to do is give thank you cards, but I think that's a little too stiff for this occasion (except for the mom who made the blanket - I definitely plan to send her a thank you card since she doesn't work here). Should I bring in something for everyone to eat like a nice cake? In addition to obviously thanking them each in person yesterday and saying how nice they were, what else would you do to show thanks?

Do the thank you cards, and bring in something nice to eat. Some really good cookies, or stop at a bakery for some donuts or sweet rolls.

Making cookies or a cake is a wonderful idea. You could also express your gratitude in a thank you email. I'm noticing this is becoming more and more common for office occasions.

You still need thank-you cards. They'll only be stiff if you write them to be stiff. I'd still bring a cake, though.

Yes, treat them to a cake and cards.