Like rock wrote more information please, would be useful.
On a hunch, it could be a brooche, now if it's Roman or medieval, or modern but very coroded I can't tell...
I've found similar items on Roman sites in the UK. I think it is a bronze fibula in the shape of a leaf. They were pins used to fasten cloaks. They normally consisted of two pieces, one on each edge of the cloak and then locked together when the cloak fastened. If yours has a pin it is more likely to be a brooch.