This floriferous Honesty (Lunaria annua) self-seeded in the front garden, most likely from the back garden where I introduced it a few years ago. It proved to be one of the sturdiest most flowery specimens I've seen and bloomed for weeks back in April as seen above.

 The distinctive papery seed heads that follow are a striking a feature in their own right. This one plant produced a great many seeds which I collected in August to sow in autumn. Despite being named Lunaria annua it is invariably biennial in my experience i.e. it produces a rosette of leaves in the first year of growth, flowers in the second then dies having produced seed.

 I sowed or scattered most of the seed directly into the garden but I also sowed a dozen in pots to grow on and transplant in the spring. NB as this photo demonstrates L. annua is a dicot i.e. produces two seed leaves, one of the characteristics of dicotyledon plants (as opposed to plants that are monocots/monocotyledon).