Strange, nondescript propeller planes flying in a circular pattern over Lanktree and Can-Ada Road..The aircraft were seen near Can-Ada and Lanktree Gulch, in Star, Idaho.I first saw the aircraft watching television upstairs. It circled multiple times, disappearing over the horizon, only to appear in about 20 seconds again, and then it continuing to circle and disappear again. It moved from a circular pattern from the left, only to wobble to the right and appear left again.I went outside and alerted my father, and we both went to get a look. It circled for about a dozen times before disappearing over the horizon for the last time.We could see in the distance another green and white flashing dot with the same lights as the plane flying near us in the distance further west from Can-Ada and Lanktree.They were definitely planes, propeller and single winged.They seemed to be flying anywhere from 400-500 feet high.The planes seemed to be flying at a strange time; it was almost completely dark outside, and they were flying much lower than any aircraft, helicopter or plane I have seen before.It would be great to know if anyone else has seen them and knows what their purpose is.