There are some ID keys to genus Silphium available online that might be useful; we'll link a couple below. Plants in the aster family (to which Silphium belongs) sometimes rely on fine details of the flower structure (like the phyllaries) to separate similar-looking species, but in the case of Silphium, foliage shape alone might be sufficient to narrow down the possibilities. Except for one species with much smaller leaves, Silphium is not native to Maryland according to most sources (there isn't complete agreement), so plants like the one pictured may have "escaped" from a garden and seeded into a natural area.

• North Carolina Botanical Garden: Flora of the Southeastern United States -- Key to Silphium
• Flora of North America -- Silphium

Our best guess is that the pictured specimen is Virginia Cup Plant, Silphium perfoliatum subspecies connatum, sometimes listed as just Silphium connatum. According to the Flora of the Southeastern United States, this subspecies can occur, albeit rarely, in Maryland.

Miri