Water Hemlock/Spotted Water Hemlock (Cicuta maculata) in fruit - 2016-8-23 Russell Peterson Urban Wildlife Refuge, Wilmington, DE

native
aka Cowbane, Poison Parsnip
The leaves are very different from Poison Hemlock (Conium maculatum).

excellent detailed depiction of various parts of the plant, including fruit
http://iowaplants.com/flora/family/Apiaceae/cicuta/c_maculata/Cicuta_maculata.html

https://en.wikipedia.org/wiki/Cicuta
"typically growing in wet meadows, along streambanks and other wet and marshy areas. These plants bear a close resemblance to other members in the family Apiaceae and may be confused with a number of other edible and poisonous plants."
also
"Water hemlock has a branched root systems with tubules, while poison hemlock has a single tap root.
and
"Another reliable method to identify water hemlock is to examine the leaf veins. Water Hemlock is unique in the Apiaceae family in that it has leaf veins which terminate in the notches between the leaf tips, rather than extend to the tip of the leaf, as is found in the leaf structure of other members of this family.