Make sure it's okay per company policy and HR. (Answer not available under cc by-sa 4It would be wise to give HR the heads up that you're putting it in the break room).0
Then leave the fundraiser box in the break room, with an indication on what organisation the fundraising is for. (But not you or your children's names).
If you're concerned about your reports feeling pressure to "donate", don't mention it's yours, and don't mention it to your reports. Then nobody feels compelled to buy any.