(Portland, OR)  --  The search for a 20-year-old Washington County woman missing since December appears to be ending in tragedy.  The Washington County Sheriff's Office says search crews recovered the body of Allyson Watterson yesterday in North Plains.  Police say a homeowner found the human remains while mowing an overgrown spot between their property and another property.  The remains have not yet been officially identified, but investigators say they're confident they belong to Watterson.  Watterson was last seen on December 22nd with her boyfriend, Ben Garland.  Watterson's mother says they were headed to a friend's home when their car broke down and they got separated.