Elliott, 36, was on a free transfer from the Wellington Phoenix. He made his MLS debut in 1999 where he stayed until 2003 with the Los Angeles Galaxy, played two years with Columbus Crew, then for England's Fulham from 2006-2008 and finally San Jose Earthquakes in 2009.
Boyens, 27, played for Toronto in 2007 and spent the past three seasons with the New York Red Bulls, who dropped him after last season.
Also agreeing to a new MLS deal was 2010 league scoring champion Chris Wondolowski, who will stay with the San Jose Earthquakes. The American scored 18 of San Jose's 34 goals last season.
Wondolowski played for San Jose in 2005, moved with the club to Houston and spent four seasons with the Dynamo before rejoining the revived Earthquakes in 2009 and last year breaking the club season goal record set by Ron Cerritos in 1999.