While there are plenty of restrictions for what you can and cannot bring in a carry-on, there are also some restrictions with checked bags. This extensive list from the TSA is a good resource for whether something can go in a carry-on, checked bag, both, or neither. Some things that can be checked: ammunition and guns, alcohol, axes and hatchets, baseball bats, Swiss army knife, snow spikes, ski poles, etc. There are also items that aren’t allowed on the plane at all, such as sparklers or fireworks, spray paint, fuels, etc.
You don’t have access to your checked bag during the flight, so make sure you put anything important, like medications or valuables, in the carry-on that you’re bringing onto the flight with you.