Is it haram to pick up an object from a loved place

Is it haram to pick up objects from a certain place so it can remind you of it? For example, picking up a leaf or a rose from a place that you like. I live next to a park and in front of the sign I picked up a rock to bring back home with me for fun, i am fully aware that nothing can protect me but Allah (swt) and only brought it to remind me of the park, is this haram?