Use green and white ribbon or mesh. You might even be able to find some patterned green & white. You can leave at that or add small footballs/basketballs/ baseballs. You could add M S U lettering.
See if you like these:
Hi Molly: Here is a site that shows how to make them: https://www.pinterest.co.uk/search/pins/?rs=ac&len=2&q=michigan%20state%20wreath If you want them to be spectacular, you can use maize and blue ribbon :) HAHAHAHA Good luck
Here is a video tutorial for you on making a collegiate wreath. Just change the colors for yours! https://www.youtube.com/watch?v=6Ah8OHZVGGU