Morels are a spongy, native delicacy found in timber and often near dead elm trees. The mushroom typically grows for only a few weeks in the spring.
The Cedar Rapids Gazette says warm weather early last spring led to a bumper crop for the mushroom.
But Dean Abel, who works in the University of Iowa's biology department, says this spring was too cold for soil to reach the temperature needed for the fungi to grow.
Abel says the rapid jump in temperature in recent days hasn't helped because the season often ends after three days above 80 degrees.