Geobound, easy there. A little education of trapping would go a long way. I totally understand the fear mongering by PETA and HSUS, but it's unfounded in most cases. Do your own research and don't believe everything you read from the anti's.
Proper name is Foothold, not leghold.
That trap isn't that old, most likely dropped (unless there was a rebar stake attached through the anchor into the ground when found) within last year or two.
Legal in many states still. What is no longer legal is 'teeth' on the jaws, but some states may still allow those too.
Hard to tell what size from the pic, could be anywhere from 1.5 (fox, coon, fisher) to 3 (bobcat, coyote).
Easiest way to unset a foothold trap...step on it. A human's shod foot is way to big to do any harm at all.