Timbers general manager/technical director Gavin Wilkinson made the announcement.
Lopez, 23, played for the Timbers' second-division side in 2009 and 2010, appearing in 23 regular-season matches. A native of Guadalajara, Mexico, Lopez was originally signed by Chivas USA in 2005 at the age of 18 and had one assist over eight games with the club from 2005-07. He has also played for the Ventura County Fusion of the Premier Development League and Mexico's Zapotlanejo during his career.
Taylor, 21, starred at the University of Tulsa, where he earned All-Conference-USA honors four times. The Edmond, Okla., native totaled eight goals and 17 assists in 82 games and led the Golden Hurricane to four consecutive NCAA Tournament appearances.
Thompson, 22, enjoyed a standout career at UC-Irvine, where he finished fifth all-time with 25 goals and also had 17 assists in 78 career games over his four years on campus. A three-time All-Big West honoree, Thompson appeared on the prestigious Hermann Trophy Watch List his senior season.