Aster (daisy) family plant, maybe some kind of cone flower.

Doesn't fit anything I can find in the Aster genus using links to the varieties via wikipedia.

The most stark difference is, there is no branching on this plant, and branching/height seems typical for Aster genus. On this unknown, all stems (maybe petioles) originate from one single point at the crown or base of the plant, and there is one leave per stem (or petiole).

Basically, it seems that's one of the unique identifying characteristics of this plant: one leaf per petiole and the petiole terminates from one single point at the ground, possibly directly at the crown/at the base of the ground (so vertical shoot/classic stem)

First-year plants often make just a bunch of single leaves like this, and leaves can change shape and size as the plant matures. Branching might not happen until it's ready to make flowers, often not until the 2nd year.

Note that I said Aster (daisy) FAMILY, including CONE FLOWERS (such as Rudbeckia). There are tens of thousands of species in the Asteraceae.

To illustrate purpleinopp's point, here's a pic of a juvenile leaf of the Cutleaf Coneflower, Rudbeckia laciniata. It closely resembles your mystery one, yet the adult foliage looks nothing like this.
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I'm pretty sure it's Rudbeckia triloba.

Had to go out of town for a couple of days. I will post back with more photos this evening if I get time. I will provide some size reference as well (coin or ruler or something).

Yes, it looked like Rudbeckia triloba to me also. In fact I have grown that one myself. But there is a huge range of composites I have not seen.