In addition to city/state guidelines, you may want to verify with the school central admin. For example, in my city, any event or fundraiser needs approval by central admin. Usually this can be done through the Principal. For our city there is a form that needs to be filled out and submitted. I've never heard of something being disapproved.
Michigan has guidelines-- you have to have a license-- you can conduct up to 3 events as long as it is in the same location off of 1 license, but there are fees for each 1. Still, the cost is not bad and we want to be on the up and up when we do an event. The other thing is there are 2 different types. 1 if you are awarding over 500.00 and 1 type if your prize is under 500.00
Best to check your area rules and regulations and give yourself enough time in case you have to apply for one.
In Texas (unless something has changed in the last year or so), a charitable org doesn't need a permit, but there are a set of strict rules it must follow for the raffle to be legal.
Check with your city/town clerks office. You probably need to apply for an annual raffle permit. You may also be required to pay a state sales tax on the amount the raffle makes so check with your particular state as well. Try the lottery commission.
It depends where you are as that's governed by state law. Raffles (and bingo) are usually consider "games of chance" and require the organization follow set rules and possibly get a permit.