You may discover three members of which kingdom from the stamps?
This might not be the right approach, but here's a possible interpretation of the first two:
Six=VI, P, Queen=ER (Elizabeth Regina=Queen Elizabeth): VIPER (snake)
10=TEN, Helvetica=CH (ISO Country code for Switzerland): TENCH (fish)
Haven't found something similar for the third stamp yet. But these seem more rebus-y to me...
Anyway, as others have found this makes the kingdom the
Here's a guess for the third stamp (not super happy with it):
101 (squinting at the two vertical borders and the round one in the middle)=CI; Hermes=VET: CIVET.
Here's a second guess for the third stamp that I have a feeling is right in the sense that it's a Dad joke/bad wordplay.
Hermes = Pan Dad. But's it is only his head, so it is PANDA...
On the 3rd image we have Hermes, the Greek god and there is a Hermes copper butterfly but unfortunately I can't get to the equal length words.
So it must be butterflies as @Kit-Ginevra already suggested.
Mercury inside a circle = Hg + O = Hog (swine)?
This might be a kind of silly answer for three, but...
It's Hermes, on a stamp so.... Her + on = Heron?
Probably a stretch, but hey it's a 5-letter animal.
The first would be a monarch. I'm guessing the others are some variety of butterfly?
Since this asking the kingdom, perhaps the kingdom is
The first stamp is a picture of Queen Elizabeth = Britain.
The second stamp has the word Helvetia, which is some kind of spider or a female personification of Switzerland = Switzerland.
The last stamp seems to be a picture of Hermes = Greece