If you can see pink petals falling around a Pokestop, that means someone has attached a lure. You’ll earn them as you progress through levels and they’re available for purchase in the Shop. Lures mean Pokemon will be attracted to the area and it’s active for 30 minutes. The benefits can be used by all trainers so be a good human and activate at a stop you think the most people could make the most of it. You can even see the name of the trainer who donated the lure so you can try and thank them in person. Look out for community days where lures will last for three hours or even longer.