Today I was outside working in my garage when I suddenly heard an airplane but couldn't see it until it popped up from trees about 1/8 mile from my house. I grabbed my phone and quickly checked my flightaware app. I saw it show an elevation only 275 ft above where I fly from my house. This is a rural area that I fly from a lot and frequently at or above what this airplane was at but under 400 ft agl. This was a twin engine airplane and was moving very quickly. I hope I could have gotten out of it's way by going full down on my controls if I was flying by due to the trees etc it would have been difficult to judge until I saw the airplane at the last moment. I certainly wouldn't have hesitated to go full down if I had been flying my drone but was curious if aircraft can fly this low legally? Thanks!