A good start is to find a local list of your natives.

AmphibiaWebs list of Delaware amphibians (but it seems strangely short):

http://www.amphibiaweb.org/cgi/amphi...-state_code=DE

This blog lists way more:

Delaware Wildlife: List of Delaware's Reptiles & Amphibians

I'm going to take a quick guess based on what I think are the light stripes down the sides and dark streaks on the back, that yours is a New Jersey Chorus Frog, Pseudacris kalmi, but you should look into it more closely:

AmphibiaWeb - Pseudacris kalmi