Complex sentence: George Washington's Mountain Road Lottery in 1768 was unsuccessful, but these rare lottery tickets bearing Washington's signature became collectors' items; one example sold for about $15,000 in 2007.
Split into simpler sentences: George Washington's Mountain Road Lottery in 1768 was unsuccessful. However, these rare lottery tickets bearing George Washington's signature have become collectors' items which sold for about $15,000 in 2007.