Echinocystis lobata, Wild Mock-cucumber
Flowers with six petals, spiny fruit 1-2" long.

Sicyos angulatus, One-seed Bur-cucumber
Flowers with five petals, spiny fruit under an inch long, in small clusters.

Melothria pendula var. pendula, Creeping Cucumber
The fruit is about 1/2" long and smooth. A North American native, but not native to Delaware. Found only on the coastal plain.

Sources: The Flora of Delaware, Herbaceous Plants of Maryland.