Green’s Dictionary of Slang

meadow muffin n.

also meadow cake, trail muffin

(US) a lump of manure.

[US] oral testimony in Lighter HDAS II.
PATH (Atlanta, GA) Sept. [Internet] Trail muffins — After many complaints of dog dooty on Atlanta trails, PATH developed a campaign designed to make it easier to pick up after dogs.
[NZ]McGill Reed Dict. of N.Z. Sl. 134: meadow cake Cow pat. ANZ.