I don't buy milk regularly, but where I live there are dairies that use glass bottles. You get charged a deposit for a new bottle, and get the money back when you return it to the store. The glass bottles are washed and reused; although the plastic cap & seal are disposable. Also, the milk sold this way is a little more expensive than the milk sold in plastic jugs or paper cartons.

Obviously this produces less trash than plastic disposable jugs. Whether it is more "environmentally friendly" depends also on energy consumption, though. Plastic jugs are really cheap to make, and they are lighter to ship than glass bottles and thus use less fuel in the delivery trucks. So there's a tradeoff, and I expect the dairies have a better idea of this tradeoff than I do.