Professor Grubbly-Plank stood waiting for the class some ten yards from Hagrid’s front door, a long trestle table in front of her laden with twigs.
The class surged forwards around the trestle table.
Harry heard her ask as they arrived at the trestle table where the group of captive Bowtruckles were scrabbling around for woodlice like so many living twigs.
He had clearly just said something highly amusing, because Crabbe, Goyle, Pansy Parkinson and the rest continued to snigger heartily as they gathered around the trestle table and, judging by the way they all kept looking over at Harry, he was able to guess the subject of the joke without too much difficulty.
There are no more uses of "trestle" in the book.
Show samples from other sources
Mother was so nervous, she bathed— into the trestle table while curtsying.
Gail Carson Levine -- Ella Enchanted
On the way back home, they were on board when the P & W had its famous crash, when the motorman was drunk and took the high trestle over the Schuylkill River at sixty miles an hour, and the whole kaboodle took a swan dive into the water.