I hope you have a fun first evening - trunk shows are always inspiring!
Does the guild website list suggestions of things to bring? For our guild, we have a raffle table (so bring loonies) and vendors (books, FQ's, notions, patterns, treasures), show & share, block of the month, and there is also often a demonstration of some sort before the meeting starts. There are also workshops held during the day of the meetings, so there is someone there for most of the day - showing up early is highly recommended :)
I hope your guild is a warm and welcoming group! I'm betting by the end of the evening, you'll have a few new friends!