"there is only one effective stretch for your back"
hmmmmm,
then i'll list some "ineffective" stretches for your back
a simple forward bend in great for your back-it helps to think of the muscles that may affect backpain as starting about your knees & going to your mid back
when doing a forward bend (whether standing or sitting) reach w/ the top of your sternum, not your nose-it may not look as deep a stretch to an observer-but you'll feel the difference
what i call a knee down twist-laying on your back raise one knee & place the ball of your foot approx. on the knee of you opposite leg, forming a triangle-with your arms extended to the side (cruciform style) take your raised knee to the floor on it's opposing side (right knee up goes down to left side)-turn your head in the opposite direction of the direction you took your knee-the goal is to have the knee touching the floor & have both shoulders lying flat on the ground, a variation of this is to do the exercise but w/ your leg extendedstraight out to the side, holding the leg at extension by the toe w/ the opposite hand of the leg you're extending
there's more (completely ineffective mind you) exercises one can do for their back-mostly various twists, but always remember to to follow a twist w/ a forward bend as this helps to realign the vertabrae
also strong abs help counter back pain try seeing how long you can hold Boat pose, where you hold your legs off the ground & balance on your sits bones keeping your back straight (but at an angle reachingbackwards) & your arms extended towards your toes forming an upside pyramid of sorts
not that any of this could possibly be effective, but i hope it at
least provides a placebo effect
(all apologies, i just couldn't help being a smartass)