Mathew Shane McFarlane, 19, had gone home and armed himself with the shovel before turning up with his mother Christine Allison Price, who shouted and swore at victim Nick Smith.
Burnley magistrates heard about the morning incident in Nelson as Groundwork Direct was carrying out roadworks.
Smith was also punched repeatedly in the face by McFarlane according to a report in the Burnley Citizen.
McFarlane admitted assault by beating. His 43-year-old mother pleaded guilty to using threatening words or behaviour.
Both live at Grove Lane, Padiham, and were bailed until September 8, for another hearing.
McFarlane said he had had a row with his boss who had told him to go home and come back on Friday to see if he still had a job.