They're Blue, Da Ba Dee Da Ba Dai
Postcard credit: "Sappho Leaping Into The Sea From The Leucadian Promontory" (Théodore Chassériau, c. 1840).
Token: "Blue Lady" (Larry Elmore?, 1992), from Tales of The Lance, published by TSR.
Stickers:
- Paradise Killer, available from Black Screen Records.
- Cherry Moon Factory.
Card: "Blue Spruce" from Arboretum (2015), card game by Dan Cassar, published by Renegade Game Studios.