Can I practice yoga if I'm not flexible?

Yoga can be practiced by anyone.  You don't even need to be able to walk or bend at the waist.  Yoga practice can be a meditation, breathwork, gentle movement with breath or a vigorous workout involving strength, deep stretching, and balance.  There are all sorts of different classes and teachers, so try a few, look at class descriptions, and if you don't find what you are looking for, consider hiring a yoga teacher for private classes.