Tim, It is difficult to say what is native with yuccas. Personal observations would suggest that they are usually found along roads and near dwellings. They certainly seem native at or near the beach and on coastal sand hills. The pods in your pic are small and extremely pinched in the middle. I really haven't been around much to observe yuccas so this could just be the northern extreme of the concava morph. the leaves of the RI plants look different also. Here is the local concava leaf morphology.