Should probably preface this from saying I was in like 4th grade at the time, but I caught a pair of batting gloves from Jeff Francoeur at Royals spring training one of the years he was with the Royals. I also got him to autograph them the next year, and that's probably the most unique thing I have. I also have a ton of Royals autographed baseballs, including a good amount from the 14-15 WS years.
ISU wise, I have autographed photos from Campbell and Purdy; and then Lazard, Butler, Montgomery and Nwangwu autographed rookie cards in their ISU uniforms.