I had no idea what this things were, so I did some research. These are oxalis (aka Wood Sorrel) pods!

This here is either a specimen of creeping/recumbent yellow wood sorrel or common yellow wood sorrel. But either way, apparently the pods EXPLODE!

“Both plants [creeping wood sorrel and common yellow wood sorrel] are perennial; however, the main difference between the two is that yellow woodsorrel spreads by below-ground rhizomes (stems that creep below the ground), and creeping woodsorrel spreads by stolons (stems that creep above the ground).”
-Source: The Cooperative Extension Service; The University of Georgia College of Agricultural and Environmental Sciences

I didn’t examine that closely when I was photographing them, so I can’t tell you which species exactly this is.