I just got 120 xp from a coin I usually get 220 from. I was recently out of hell and hadn't got my mood up yet so that may have accounted for the lower xp.
That same coin used to yield much lower xp when I was at a lower level.
A quick tp to the ancestral lands is usually effective in getting mood up after dying. I do wish people would leave the mood coins for others if their mood is already very high. Mood doesn't drop in the game so easily as energy does. I also try to remember to leave the current coins alone in areas where there are likely lots of new players. Not worth jumping for and I'd rather spend my daily limit on xp coins.
Today I got 2000+ xp from a quoin in a well travelled location. I believe these special quoins accumulate value like a well aged wine. XP coins are also effected by mood.
I have been making an effort to explore the world and find more special quoins. The first one I found was in Ajaya Bliss, slightly out of the way of where sparkly rocks spawn.
It's too bad we can't pool our efforts more, as this is a rather secretive club by necessity. :)
There are 2 large XP coins in The Great Haul. The street coins values seem random to me, although the ones that are hard to get to "sometimes" pays a bit better.
The coin values scale with your level. So if your level number isn't up there, you won't be finding 1800 XP coins like mentioned above.
The ancestral lands have good coin values, but there are larger coin values (relatively) in other areas. You can also find favor and timer coins in non-ancestral land places. But the respawn rates are quite low so you may never realize a certain place spawns a valuable coin unless you visit often.