The Iowa seed law requires labeling of lawn seed containers as to "Fine Textured Grasses" and "Coarse Kinds." Here are details plus information you may need to select the seed to produce the kind of lawn you want.
Everson, L. E. and Roberts, Eliot C.
"Seed for YOUR Lawn,"
Iowa Farm Science: Vol. 18
, Article 3.
Available at: https://lib.dr.iastate.edu/farmscience/vol18/iss9/3