The 20th annual Memorial Weekend  in the Wine Country begins tomorrow with more than 150 wineries in the Willamette Valley opening their doors for special events and tastings.   Wineries and tasting rooms will be open to the public from 11 a.m. to 5 p.m. Saturday through Monday, May 29 to 31.   Some will offer food and live music.   This is also a great time to meet winemakers personally.