Got concrete?

Has anyone noticed around campus the random squares of concrete off the sidewalks? They are surrounded by hay, which of course, are to help protect the grass that is to be growing there but why a concrete slab? I have no idea what they could be. Does anyone know or have the slightest idea about it? I would greatly appreciate it if the university would send us an e-mail and inform us about it. I'm curious. However, the good news is that our tuition is going to good use!