The Museum Market is a large open-air market open to everyone and usually opens the 3rd or 4th Sunday of the month but check their website for the exact dates. Besides one or two months, they're there throughout the year. It's pretty large and stretches on either side of that long pond in that area in front of the Rijksmuseum. The main thing is that the pond there is also ICE* Amsterdam (giant outdoor ice-skating rink) takes place, and it was decided that the Market couldn't be opened at the same time as it.
If you're planning a museum day in the Museumplein Park area where the Van Gogh, Rijks, Moco, and Stedelijk museums (and then some) are, I would recommend trying to go on a day the Museum Market is there. They're right in the center of it all, so on top of all of the museums, it's a convenient way to get a look at local artists, designers, and food vendors. It makes for very convenient souvenir shopping as they have a HUGE range of art fashion, accessories, jewelry, household stuff, toys, and miscellaneous little things that I enjoyed a bit more than what I found in the surrounding museums' souvenir shops.
If you're looking for food, there are a few food vendors with small things. We were actually coming from the Van Gogh Museum and were attracted to the food carts. Besides the usual sweets and baked good stands, I finally got the chance to try bitterballens and there was this Mr. Brasa barbeque stand that we found pretty interesting. There isn't really a lot of benches/tables, but there are a few.
Overall, fun addition that I definitely think you should include in your Amsterdam museum-hopping plans. read more