Amsterdam's street markets are some of the best in Northern Europe. The standout is the Albert Cuyp Market in De Pijp (Albert Cuypstraat, Mon-Sat 9:00-17:00), with over 300 stalls selling everything from Surinamese roti and fresh stroopwafels to vintage clothing and cheap socks. It's the city's largest and most diverse outdoor market.
The Waterlooplein Flea Market (Mon-Sat) near Rembrandt House is Amsterdam's oldest flea market, good for secondhand books, vinyl, and random curiosities. The Noordermarkt on Saturday morning is the organic farmers' market where locals actually shop, with excellent bread, cheese, and seasonal produce. On Monday mornings the same square hosts a fabric and vintage market.
For flowers, the floating Bloemenmarkt on the Singel canal is touristy but still worth a walk-through for bulbs to take home.