Savannah Sparrow (Passercilus sandwichensis)
I find many sparrows difficult to identify, but not this one. When I see a yellow patch by a sparrow's eye, I am pretty sure I am looking at a Savannah Sparrow. (FYI: A birder friend has just told me that White-throated Sparrows also have a yellow patch. Thanks, Paul!) But these two are Savannah Sparrows.
Savannah Sparrows are are one of the most common sparrows across North America.
Hopping about in some grass
This sparrow is likely foraging for seeds. However during breeding season Savanah Sparrows also eat insects.