How can I make something out of my tree stumps?

Not sure if you are looking to make something out of the wood or the trees stumps still in the ground. 4 feet high is pretty high. How about planters on top with vines that trail down mixed with flower pots.

You could dig them out and use as planters

Cut them to table height and use as patio tables?

With how tall the stumps are, you can screw flower pots at a tilted angle to them making a flower stand with your favorite flowers. You can paint the stumps and make a stacking circle of pots. Again add your favorite flowers.