I am not trying to be a downer, but the 'staining' on the duck stamp implies to me that it probably has no gum on the reverse (like maybe something spilled on it, resulting in the red staining) or, at best, disturbed gum. Its real value (based on condition) would be quite low - you might get $5 or $10 for it if you could find a buyer on, say, eBay
. If it is creased, torn, or thinned (can't tell from the scan, but quite possible given the visible condition) it would be worth less than that. The other stamps are quite common and not worth much (pennies). I am sorry.
ETA: A 'genuine' used Duck stamp has a signature - I don't see one here. Someone may have interest if it is canceled with a clear town cancellation, but I don't see that either. It appears to be somewhere between (or outside of the spectrum) used and unused, which is not a good thing.