Hi Beth,
Herne Hill Market also comes to mind. One could check out their Blackbird Bakery, Agua na Boca (Brazilian), Portland Scallop Company, Brambletye Farms and La Tartiflette. Sometimes, crafters who create things from rare fossils are also in attendance there.
I also second Gerry's combo of Brick Lane and Spitalfields. We rented literally a block away from Brick Lane. Thus, easy access to its weekend market---we went twice. Some of our faves there: the award-winning Spanish Caravan booth; Dark Sugars (permanent chocolate shop).
Trumans likewise. Faves there at its Sunday Upmarket: Aunty Audreys Red Sorrell; Nina's cakes; City Juice (flavored cane juices); the Lithuanian stroganoff-making couple; Viv's Brazilian.
Spitalfields' indoors 'Kitchen Section': Chai Guys, Sud Italia mobile oven pizza (try zucca), Pleasant Lady (Chinese pancakes), Dumpling Shack, Pilpel falafel, Meson les Barilles (Spanish). *Spitalfields does an Antique show on Thursdays, plus a Vintage Show on Saturdays--check schedules.
Boxpark: we went back to the Brazilian Acai shop a number of times.
Those interested in the Rough Trade music shop can see a photo that I took there at a Q&A with the band 'Porcupine Tree' (never cuddle a porcupine). That image is in our loooong TR titled 'Back to Brick: a London TR'.
Just google 'zebec Fodors Back to Brick'. There is additional market coverage in it too.
I am done. the end.