I have a vegetable that has come up as a volunteer in my vegetable garden. The foiliage looks similiar to a cantelope. It has rounded edges instead of pointed as with some cukes and squashes. The fruit is about the size of a baseball and is green. It has a taste similar to cukes, but I detect a sweeter taste. I have never seen these before, don't know how they made their way into my garden, but maybe some of you long timers or knowledgeble gardners can help me out.

Thanks!