My friends and I were sitting out at our picnic table and as always I watch the skies when a commercial aiircraft flies overhead. As we were sitting there my friend says whats that? I immediatly looked up to see a object at approximatly 15,000 ft.. I guess this altitude because there was a commercial aircraft at approximatly 30,000 heading South. There was a light cloud cover with breaks in between and visibility was good in these breaks. My friend and I saw an object traveling in a northbound direction.I have not seen anything that would remotely come close to what I saw.I havebeen observing aircraft for over 40 years. The object had an estimated wingspan of 200 to 250ft..It was Black in color with a cresent shaped wing.It appeared to have a Fuuselage in the center with a series of concave shapes on the trailing edge of the wing.The object was not moving at a high rate of speed but rather seemed to be motionless for a brief moment. As the clouds passed to the south a break opened and it appeared again only for a quick moment.It was then that it disappeared to the north rapidly above the cloud cover.My friend will not come forward in this matter and I have since moved to Spokane,Wa.Please feel free to contact me. I have more to teell about other incidences that I have encountered over the years.I manufactured small aircraft for nearly 7 years so i am not a complete nut.