The Lawndale High track team is the school's track team, run by Ms. Morris. While not shown outside of "See Jane Run", in that episode they were presented as regularly having track meets against other schools and being popular kids (when they're winning, at least); their continued success was seen as important to the school and they get favours from the faculty.
Known members include Evan, the recurring background characters Les, Jennifer, and "Chipmunk", and two rarely seen, unnamed black students nicknamed "Track Guy" (a tuckerization of character designer Kirk-Albert Etienne) and "Brown Blouse".
Jane Lane temporarily joined the team and became popular at school as a result. When she tried to quit, Ms Morris tried to blackmail her into rejoining by threatening to flunk her in Maths - the rest of the track team stood alongside Morris when she tried this. Notably, both Angela Li and the PTA were said to be aware of such grade-fixing antics.
The team won a trophy when Jane was a member. Track teams win trophies at important meets and if they're the overall winner in previous meets, so Jane was in the team for a while - and Morris was right, they really did her!