Garner had handed the Pilgrims a third minute lead at the sun-drenched Jakemans Stadium although his effort was cancelled out by Sunderland's multi-million pound striker Danny Graham nine minutes after the break.
United bossed proceedings in terms of chances created, with former loanee Liam Agnew who indeed hit the bar for the Black Cats, twice denying Carl Piergianni on the line.
GARNER had headed the Pilgrims into the lead with 150 seconds on the clock when he bulleted Rene Steer's cross beyond the grasp of keeper Peter Burke.
Sunderland levelled on 54 minutes when GRAHAM capitalised on some indecision in the United rearguard to round Matt Gledhill and grab a straightforward equaliser.
Boston (4-4-2): Matt Gledhill; Zak Mills (Connor Smythe 82), Karlton Watson (Stefan Galinski 64), Carl Piergianni (Duran Reynolds 64), Rene Steer; Jamie McGhee (Kaine Felix 60), Jay Dowie (Michael Hollingsworth 75), Jake Hall (Danny Meadows 60), Jack Barlow (Conor Marshall 60); Scott Garner (Charley Sanders 82), Dayle Southwell (David Fallah 68). Sub (not used): Sam Vince (gk).
Sunderland (4-4-2): Peter Burke (Max Stryjek 46); Michael Ledger, Tom McNamee, Scott Harrison, David Ferguson (Tommy Robson 46); Duncan Watmore, Martin Smith (David Moberg Karlsson 46), Liam Agnew, George Honeyman (Tom Beadling 68); Danny Graham (Lyndon Gooch 68), Carl Lawson. Sub (not used): Andrew Cartwright.
Referee: John Brooks.
Attendance: 450.
PIC: Tim Hoff.