Yes, the city of Springfield does have a flag.  The City of Springfield's web site contains this brief article about the flag:

“The history of Springfield's flag dates back to early 1938, when Phoebe Hensley, a skilled seamstress and active member of the Community Business and Professional Women's Club, was commissioned to handcraft the first flag.

The original banner was 4" x 6" in size and was made of one yard each of red, white and blue heavy cotton. The total cost was 75 cents.

The official Springfield flag contains a red, white and blue bar with SPRINGFIELD, MISSOURI appliqued on the center white bar.

A large white star is in each of the four corners. Each star and stripe has significance. The red and blue bars stand for cooperation and civic pride.

The white bar stands for the renown Springfield has received for its achievements, which are represented by the four stars of: Religion, Home, Education, & Industry.

A color picture of the flag, along with historical information, can be found on Flags of the World.