Here's a couple covers I know nothing about, are these US covers? I noticed the second one is airmail and has a United Nations cancel from New York, is there any value to either of these? Hope I've asked this in the right section.
A Minus ... that they do not have any cachet at all. Made in huge quantities well beyond current demand.
A Plus ... among specialists, there is typically a bump in value for foreign destinations ... the bump depending on the exoticness of the destination. Canada is no doubt the most common. And there would have to be some processing marks of some sort on the back to prove either one went into the live mail stream ... as opposed to a hand-back sent under cover at a later time - or the address added later.
Hounddog Bill: You have already received some good advice. However, the bottom FDC is Scott's U.N. C1, the first U.N. air mail stamp. I would not want to throw it out with the bath water. Respectfully submitted: jrc
jrc531 - I had 5-6 years ago, acquired within a large auction lot - a brilliant collection of UN very early plate block FDCs - and found ZERO interest on eBay or elsewhere. I'd value UN FDCs and most postage worthless these days. (This is sad BTW - their postage issues and FDC cover quality were exceptional)