Taken from link https://collectingtokens.wordpress.com/2011/02/22/little-phoebe/

Little Phoebe
n : the cardinal number that is the sum of four and one (syn: five,
5, V, cinque, quint, quintet, fivesome, quintuplet,
pentad, fin, Phoebe, Little Phoebe)

Where the above page cites: Dictionary of the American West: Over 5,000 Terms and Expressions from Aarigaa! to Zopilote

Win Blevins Author.

I didn't go further. I'll just make my base judgement for now, that it's archaic or obscure. (time for bed)

Doesn't the postcard show 3 and 2?

One mystery leads to another?