Our bumpy mystery seeds from last week were from the white campion, Silene latifolia.
The white campion was introduced from Europe and now is a common wildflower, particularly in the Northeast. It generally grows as an annual.
It is easily recognized by the swollen calyx of the female flower, which has a pink-purplish tinge.
The flower petals are bright white.
The seed capsule forms from the calyx.
(Public domain photograph of mature seeds from Wikimedia.) Inside the seeds are covered with small bulges.
The leaves form opposite pairs along the stems.
White campion is a common flower that is easy to overlook. Does it grow where you live?