Review the item:
Syed finally decided to clean out his disorganized book bag, old U.S. Government
handouts,
math notes from Intermediate Algebra, leaky ballpoint pens, and a
smashed banana littered the inside.
Old U.S. Government handouts is one item in a series of four. Math notes from Intermediate Algebra is the second item in the series. You need a comma to separate one item from the other.