You could regard them as free plants, but you have no way to know what the quality, or with the pumpkin/squash type thing, even what general kind you have until they've grown for a couple months. Since we don't know your location, we don't know if you even have three months of growing season left to invest on these.
Bottom line- many seeds sprout in compost and I agree, there's just best dug back into compost.
