Was wandering if anyone could tell me what this is it very round and rattles 

Looks like river rock, but you said it rattles which points towards some type of fossilized egg.  Or could be a geode - sometimes the interior crystals will get knocked loose and rattle.  Would help to know the location found, if you are okay with giving geographic information.

Edited February 20, 20241 yr by TheVat

Here's a similar thread from a few years back: Round rock, makes a rattling noise