a mushroom rival What could the expression 'a mushroom rival' mean? Perhaps, the rival isn't real, hypothetic? But why is it 'mushroom'? The context: There are 2 young girls who are cousins and friends. One of them is going to be married soon. Her husband-to-be has a sister whom she's never met so she is enquiring him about her new relative. Her friend is listening to their conversation. The author's comment about this: "...if she had not been very proud she might have almost felt jealous of the mushroom rival".I think I got it. Mushroom here means rapidly growing. I think sometimes just typing the question on italki makes it clearer ;) 'She' is the girl who isn't going to be married.