These back stretches are for general lower back pain. If you have a specific injury or diagnosis, some of these might not be appropriate, so check with your doctor or physical therapist first.
The first three lower back stretches are the pelvic tilt, the cat/dog stretch, and trunk rotation stretch. These are a great way to start with to loosen up the low back and core muscles.
The fourth low back stretch is a trunk rotation with crossing the leg over the body. This will give you more of a stretch in your low back, and it might also adjust your back.
The next back pain stretches for the lower back are hamstring and hip flexor stretches. When either of these are tight, they can pull the pelvis one way or the other, and this can cause low back pain. Stretching them should relieve the tightness.
The prone press, single knee to chest, and double knee to chest are also great stretches. Make sure you know what is going on with your back though since for certain diagnoses, you might not want to do these.
The last low back stretch is the prayer stretch or child’s pose. It does a great job of stretching your whole body from your shoulders, upper back, lower back, hips, knees, and even your feet.