It'll be a toad, sometimes called a toad-frog, and in North America there are several toad species. The American Toad, Bufo americanus, resides in most of eastern North America, except for the Deep South. Woodhouse's Toad, Bufo woodhousei, is found in much of the same area, plus it's also found in much of the Deep South, the Great Plains and Rockies. These two toads are the amphibians most likely to appear in most North American backyards. They're so similar that you may need to study them awhile with field guide in hand to figure out which species you have. In fact, the various species of toads often are notoriously hard to distinguish.
The two most conspicuous features distinguishing toads from frogs can be seen in the picture at the left showing a view of a toad's head, from above. First, the toad's skin is very warty, while the skin of most frogs is smooth. Second, notice the four very large, bulging bumps. The top two are the toad's bulging eyes. The bottom two are poison-secreting glands called parotoid glands. If your cat ever attacks a toad, it probably won't do so again, for poison from these glands makes the toad-chewing experience a bitter one. The white, viscous poison inflames the mouth and throat, causes nausea, irregular heartbeat and, rarely, even death. Frogs don't have these glands.
Also, true frogs have webbed toes and treefrogs have webbing and, often, toe pads, but in the pictures here you can see that a toad's feet lack both webbing and pads. At the left is a toad's front foot, and at the right is its back foot. On both feet, note the large, yellowish bumps. These are tubercles, which help the toad to dig.
Finally, you don't get warts by handling toads!
You might enjoy reading Naturalist Jim's fieldnotes on frogs and toads.
You can review books about frogs and toads available at Amazon.com by clicking here.