Many benefits to Yoga
Start slow, on your own or with a partner or instructor ( more fun with a partner! )
the link below is a good starter - please check with your Doctor first.

Stretching hip flexors /glutes -  wow, so many people have mentioned this to me lately! Seems it is an issue with many.  
Daily stretching has SO many benefits.  
There are a few Yoga moves that are great for hip flexors, you will see those on the link below.
Also, i found a good Youtube video of a gal doing The Glute Stretch -  
I couldn't link both  links, so go to Google  and search 'how to do the Glute stretch, You tube Livestrong'  and that should get you there! It really is a good video of a good stretch
I do it twice daily
go SLOOOOOW with stretches and yoga! can't stress that enough - no rush, no bouncing, no pulling,  just real slow, and if any pain, back away slowly.
best wishes to your health X

Stretching is good and Yoga is great, but living with back pain is terrible. Many years ago I fell off a ladder and did something to my back. It was painful and my back muscles tightened up so bad that I could hardly walk. Every time I shifted my weight from one side to the other the pain peaked. I went to a chiropractor for weeks, and nothing he did seemed to help. I had a stick shift car at that time and shifting gears was a nightmare. I lived with this pain for about nine months, and in January of the following year, I caught a bad cold. I always took vitamin C to knock out a cold, and this time was no different. I took a lot of it because that was what worked. The cold went away in about three days and the back pain went with it. All of a sudden the pain was gone, completely gone; I felt like a kid again. I learned first hand that vitamin C was the key to unlocking a stiff back. Last Sunday I went golfing with a neighbor and twisted my back. It hurt a lot and ruined my game, but that night when I went to bed, I took 6000mg of vitamin C. The next morning I felt a little better, but that afternoon I felt great. I don’t live with back pain anymore.

...something. Don't need weight. Use a piece of 2x4 or a book. You want whatever it is to be about 2 inches high. Make sure it can't slide. Stand with your heels up on the 2x4, toes on the floor. Do 10 to 15 squats. Make sure your knees are even with your toes when at the lowest point. This helps stretch the back and gluts. It's especially good for relieving nerve pressure from bulging disc. If you are a gym member they have things you can use to elevate your heels.

Yes,
One of my favorite partner stretching techniques involve sitting face to face with your legs stretched out in from of you feet touching. You can bend the knees if your not that flexible yet. you clasp arms in between each other and take turns pulling and stretching each other. One partner leans forward as the other partner pulls to deepen the stretch. then take turns. One of the most important parts is to combine the stretching with synchronized breathing within the stretch. Example_ the person being pulled take a deep breath on at the beginning and exhales slowly and deeply as they are pulled and stretched. Dropping down into the body and deeper in to the stretch with each breath.  

I would also combine this stretching with massage afterwards to help loosen and relax the back.Take turns with partner massage where one simply receives the massage without any reciprocation for maximum relaxation. So many times people are in such a hurry to get in, get on, get off they don't realize that the whole body is one big erogenous zone.