in the mud again

We went to the park yesterday (we go most Tuesdays when it's not too hot to bare) and it had stormed good the night before. At least that's what it appeared, I didn't wake up, but there was water EVERYWHERE. Hannah found the "pound" under one of the play structures and went "swimming" she was covered with mud, both front and back. Evie has started enjoy the park as she can walk from one play structure to the next, well, there was major amounts of water in between and this mad an exciting sound when she splashed in it, so she too had a marvelous time playing in the water and was wet from head to foot as well. Of course I didn't have my camera, so no pictures. Sorry :-( But can you tell me why out of about 10 kids at the park mine are the only ones drawn to the mud?