Creeping Cucumber (Melothria pendula). Perfect for a dollhouse if you need a tiny watermelon of dollhouse scale. If only they would last. It is native to southeastern North America.
With flowers of yellow, just 1/4 inch across. Though it is native it will be treated as a weed here. A weed, after all is a plant that grows where you don’t want it. And that is what this plant has done. Moved itself into the vegetable garden unbidden.
Creeping Cucumber is indeed in the cucumber family (Cucurbitaceae) and its leaves resemble cucumbers that you’re used to seeing in the vegetable garden. It tastes like those cucumbers that you grow in the garden too. But use caution. Only eat the light colored Creeping Cucumbers. The ones that look like tiny watermelons. As they mature they will darken to a purple-black. At this stage they are an incredibly powerful laxative.