She looks so much like a hen that I have, and I haven't figured out what mine is either. The above is correct, Welsummers don't have slate legs, but I don't agree its an Easter Egger either. Slate legs does not automatically make a bird an EE, and like my hen, yours has a straight comb instead of a pea comb. Mine lays a cream colored egg, by the way. I'll see if I can dig up a pic to compare.
I don't think she's an OEGB, while she is a bantam (I think, at least), she's much larger than my OEGB and Japanese bantams now. I would go out and get a more recent picture of her, but she's broody at the moment :/
I found mine orphaned in my horse pasture. My neighbor has many chickens of different breeds. Some say game hen. But is that a breed of its own? It was a hatchling when I found it. Brown racing stripe fuzz with Orange beak and legs, it's legs are now almost grey and her beak black. She's friendly that's for sure. But she wouldn't ever take to any other chickens....just humans. Hoping she'll wean easy. Need her to start nesting asap so she will take to her coop before winter.