posted 12 years ago
I'm fairly sure this is indeed Field Pennycress - the notch in the circular seed pod is a field mark. In my region, Shepherd's Purse has a heart-shaped seed pod that's smaller. There are several other related small mustards, but I'm fairly confident with that ID - and to my knowledge, all mustards are edible (if not all good tasting) - though I'm happy to be corrected on that.
I like this plant. It loves disturbed soil, and if it's present, even if you mulch, you'll get a bit here and there. The leaves before it goes to seed have a nutty/mustardy taste in salads which I quite like. That taste gets stronger when they go to seed, but in my opinion is still okay. I'm sure you can use it as a cooked green, and can probably eat the tenderest part of the stem when it's growing quickly either raw or steamed. Flowerheads taste good to me too - though a bit strong flavoured. I've had people taste this and love it, and read descriptions that say it tastes awful. Try a small bit to make sure you like it.
In good conditions (full sun, various soil types) it gets very big, and produces many seed pods. In the past, I've gathered a bunch of big plants and hung them to dry, then gathered the seeds out of them. When ground, the dried seeds make a very nice seasoning a bit like black pepper (Pennycress is closely related to Peppergrass, as well as Shepherd's Purse). There's likely not much need to replant seed - it'll be back!
Of course - make sure you're confident with the ID yourself before consuming it.