Spadefoot Toad
Scaphiopus holbrookii holbrookii
I confess that I have never encountered this rarest (Endangered) of the New England Amphibians, yet. This is my holy grail.
The problem with this species is a) it spends much of the time below the ground, b) there are not that many of them, and c) your best chance of finding them is during a period of heavy rain - thunder's a plus.
Spadefoots prefer sandy habitats. A good torrential rain storm occuring between spring and fall brings them to the surface where they feed and breed in temporary pools. The tadpoles develop quickly, racing the receding water.