A key to a healthy stable back is hip mobility. The ability to move the hip in large degrees of motion so we can jump, crawl and move our body easily. Low back pain can simply just be lack of good hip mobility. Here is a great video demonstrating easy ways to improve your hip mobility.
I am not a big fan of stretching as it doesn’t really deal with why the tightness is there in the first place, but if you do have back pain that can be a great simple stretch to start with that will give you temporay relief of you back pain.
One of the biggest issues with low back pain is tight hip flexors. But just stretching your tight hip flexors is not always the best option. This video gives you a great demonstration on how to first relax you tight hip flexors before we can fix the problem in the low back.