If you're in eastern Pennsylvania and happen to find a toad, most likely it is an American Toad. There are a few other species like the Fowler's Toad, but in most areas the American Toad outnumbers and even hybridizes with the other toads.
I have been raising American Toads (and probably Southern Toads) for years in a very small pond with tadpoles I would obtain from ebay. They disappeared into the yard and were rarely seen as adults.
Now that I have the bigger pond, there are new possibilities.
I work a toad rescue called the Toad Detour in Roxborough (Philadelphia). After a busy night of helping the toads get across the road I invariably find more toads crossing on my drive out. These get put into a bucket and driven to my pond. The males tend to stay, the females tend to wander off.
I also found a reliable place for gathering toad tadpoles right in King of Prussia. Toads lay their eggs in temporary puddles. They were reasonably easy to gather and transport to my pond where they didn't have to worry about the pond drying up.
In the first "stocking" year year I had more than 100 tadpoles in the pond and in April we'd see the little toadlets hopping across the walkway and into the grass. They take about three years to mature.
The male toads call out for the females to come find them. They are very loud.
2026 Update - I have completely established American Toads in my neighborhood and they come back to the pond every spring. I have thousands of toad tadpoles in the pond every spring. I see toads in my yard on rainy nights. Success