Foamy Yellow Piles on Mulch? It's Harmless Slime Mold

Those foamy yellow piles are slime mold on wood mulch — likely from heavy watering (new sod?). Slime mold thrives in abundant moisture.

No action needed. It's harmless and disappears when weather warms and dries. If it persists despite reduced watering, poor drainage may be the issue — water those spots less. Meanwhile, rake the piles to break them up for appearance. Freshly ground/chipped mulch is more prone; let it age a year before spreading.