You can make a great presentation with the ball & glove as big, dimensional focal points. Arrange the other items around/among them.
Use an acrylic box, and raise the flat items off the background (in mini-frames made of fillets, perhaps).
I suggest, to mount the ball, make a nest hole 1-1/2" -- 2" diameter and stretch matching nylon tulle over it. Wrap the ball like a lollipop, pull the ends throught the nest hole, and secure the tulle to the back of the mount board with hotmelt glue.
To mount the glove, use clear film straps in at least three supportive points.
Sounds like a fun project. Welcome to The G.