May 1st is a national celebration in Finland called Vappu. On Vappu you will be able to see many Fins walking around in white caps and their university overalls (in Finland most subjects offer coloured overalls that students buy and sow patches on over their time in university). There are also some traditional foods that can be tried at this time:

• sima - a sweet and mildly alcoholic drink
• tippaleipä - deep fried cake dusted with powered sugar
• munkki - Finnish donuts

For more information see: http://www.studyinfinland.fi/living_in_finland/way_of_life/festivities/vappu