What are some of the most successful fundraisers you've been involved with?

Now that our trip location has been settled, my kids need to fundraise!
Our trip to Europe is independent of our school district, so it must be paid for entirely by fundraising and the kids’ families…we have some ideas for fundraisers but I figured my fellow jellies would have some great ideas, too.
What’s worked for you?
We are a small town of around 10,000, bordering a bigger city of about 100k…if that helps.