The second set of pictures are of sunflowers in a park wetland area about an hour from here.

Key D - perennial sunflowers with leafy stems and yellow disk flowers
1 Stems below the capitulescence glabrous or nearly so, sometimes glaucous.
2 Leaves whorled at principal nodes, either alternate or opposite at other nodes ...................................................................... ..... H. verticillatus
2 Leaves either alternate or opposite (or both).
3 Leaves grayish-green or bluish green in color, sessile, and abaxially glabrous and glaucous.
4 Rays 5-10; leaves glabrous or glabrate adaxially, smooth or only slightly rough to the touch; phyllaries 2-3 mm wide .... H. laevigatus
4 Rays 10-14; leaves strumose adaxially, rough to the touch; phyllaries 3.5-4.5 mm wide .........................................................H. eggertii
3 Leaves light to dark green, sometimes whitish abaxially, but not grayish or bluish green in color; leaves sessile or petiolate, glabrous or
pubescent.
5 Leaves linear-lanceolate, with only a single main vein ...................................................................... ......................................... H. smithii
5 Leaves linear-lanceolate to lanceolate, lance-ovate, or ovate, triplinerved at base.
6 Rays few, usually 5 or 8; heads small, the involucres 9 mm broad or less.
7 Leaves abaxially whitish in color and glabrous and glaucous, lacking subsessile glandular trichomes ("resin dots") .....................
...................................................................... ...................................................................... ..................................... H. glaucophyllus
7 Leaves abaxially greenish in color, usually tomentulose (sometimes glabrate), with abundant subsessile glandular trichomes .....
...................................................................... ...................................................................... .................................... H. microcephalus
6 Rays usually 10 or more in larger heads; heads larger, the involucres usually > 9 mm broad.

8 Leaves sessile, rounded to cordate at base, and trinerved, with the 2 lateral veins diverging from the midrib at the very base of
the leaf ...................................................................... ...................................................................... .............................. H. divaricatus
8 Leaves sessile to petiolate, but narrowing gradually to base and triplinerved, the 2 lateral veins diverging from the midrib above
the base of the blade.
9 Anther appendages yellow.
10 Leave blade lanceolate to lance-ovate, sessile to petiolate but the petiole usually < 1/4 as long as the blade; phyllaries not
conspicuously graduated and imbricate, usually loose and spreading .......................................................... H. grosseserratus
10 Leaf blade ovate to elliptic, with a distinct petiole usually > 2 cm long and 1/2 as long as blade or longer; phyllaries
conspicuously graduated and imbricate, usually appressed, not exceeding disk ................. H. occidentalis ssp. occidentalis
9 Anther appendages dark or reddish-brown.
11 Plants producing abundant tubers; leaves subsessile, the petioles < 1 cm long; [endemic to the Piedmont of NC and SC] ...
...................................................................... ...................................................................... ................................ H. schweinitzii
11 Plants rhizomatous, but not producing tubers; leaves petiolate, the petioles 1-5 cm long; [collectively widespread in our
area].
12 Phyllaries equal to or slightly exceeding disk, apex acute; leaves moderately serrate to entire, with a petiole 1-3 cm
long, and abaxially with usually abundant subsessile glandular trichomes ("resin dots") ............................. H. strumosus
12 Longer phyllaries usually exceeding disk by half their length or more, apex acuminate; larger leaves moderately to
conspicuously serrate, with a petiole 2-5 cm long, and abaxially with usually relatively few subsessile glandular
trichomes ...................................................................... ...................................................................... ........... H. decapetalus

How did you come by this plant, by the way? Was it purchased or growing wild?

I wonder if the planted specimen is a hybrid, such as Helianthus x multiflorus.