2. A dry, thin and crisp savoury biscuit? - US origin.
3. A disparaging term for a white person (usually one living in the American south, and usually one who is poor, and most likely with a socially 'conservative' viewpoint) - US origin.
4. An American alternative rock band, fronted by former [Camper Van Beethoven]? signer Dave Lowery. They had a few minor hits in the early 1990's, including Teen Angst (What the World Needs Now) and Low. Though still a going concern, they have essentially been a cult act since about 1995.
The general public will be much more familiar with senses 2 and 3 than with 1 and 4.