does a usa .3 stamp conestoga wagon have any value and an audubon american artist stamp with birds of paradise I think they are blue birds .5 us postage at the very bottom,and a .10 stampwith two flags and the words united states at the bottom also it is attached to clipping of the envelope it was mailed with the postmark on the clipping has us postal service 476 -pm 22 jul 1975