Pumpkin Relative (cucurbitaceae): It is difficult without seeing the plants flowers or fruits, but it appears this plant is in the cucurbitaceae family. Please send back another picture when it flowers or when it fruits so we can make a more detailed identification. It could be zucchini, pumpkin, melon?
Burdock (arctium lappa): This is burdock, a biennial weed with large leaves and a giant roots (eaten in Japan as gobo). It's very hard to get rid of because the root is so large. Flower stalks can be 4-5 feet tall. The individual flowers look like thistle flowers.