Plunkett took three for 43 after Sri Lanka had won the toss and elected to bat.
At the close England were 138 for three after off-spinner Muttiah Muralitharan took two late wickets.
Sri Lanka, who fought back to draw the first Test at Lord's after being asked to follow on, would have been further humiliated had it not been for Chaminda Vaas (30 not out) and Lasith Malinga (26) who added 50 for the ninth wicket.
