Three highly attractive palms are generally considered fire-safe as long as their dry fronds are removed in a timely manner.
Perhaps the most deadly plant you may already have in your yard is the Sago palm/Cycas revoluta. It is toxic to humans and pets. Oddly enough, the Sago, despite its structure, is not a real palm tree.
Sago palm (Cycas revoluta), although not a true palm, is another species worthy of consideration as a centerpiece for your planter. You would, however, want to procure a mature specimen ...