If you are lifting outside a squat rack with bumper plates, it's completely fine to drop the bar to the ground behind you. (nerdfitness.com)
I'm looking primarily for bumper plates because if I went with steel plates I'd just buy them used locally. (kingofthegym.com)
You'll want bumper plates because they are safe to drop and throw around, and they will not be as loud as your typical iron plates. (fitnessdoctrine.com)