There's a mowed area around the pavilion, and with the abundance of sun, and low elevation and humidity down by the river, this is prime weed habitat. The greens are mostly clover, chickweed, and dead nettle, with scallions (wild onion/wild garlic) all across the mowed lawn area. There are dandelions also, but with the cloudy skies, only a few are in bloom.
Look how lush the chickweed is:
And the dead-nettle around objects the mower couldn't reach: