Check the ASPCA site -- if you scroll down you'll see links to both their toxic plants list and non-toxic plants list. With ball pythons, you don't have to worry about those that are only toxic if ingested, at least if you feed outside the cage. You do need to worry about those that are toxic on contact, including those with toxic sap as the snake will occasionally break off branches or leaves.

Also, despite any controversy over Melissa Kaplan, her site has an excellent resource on plants specifically for reptile keepers.