By the main Brasilia cathedral there are those stalls that sell dried flowers from the "cerrado" wich is the landscape of the area. As they are dried they last long, but you have to pack them well to take home.
If your interest is architecture it worth a visit to Brasilia and meet Lucio Costa Athos Bulhões and Oscar Niemayer´s work. But, take your time and guide visit all the official buildings inside to appreciate it.
I'm a bit embarassed to say,but I really don't like Brasilia,even most architectures keep considering it the top of modern brazilian architecture.
I agree it wasn't easy,for sure,to project a whole......