I have replaced the information in my original post with the Trinket section of the Resto Shaman TTT. This has the most accurate and up-to-date information.
How to calculate the value of on-use trinkets:
Take the amount of additional healing and multiple by the duration of the buff. Then divide by the cooldown. Let’s use
[Winged Talisman] as an example
346*20/120 = 57.7 spellpower
To ensure you use on-use trinkets every time the cooldown is available, you can create a macro to use them each time you cast Earth Shield, Chain Heal or another spell.
Trinkets listed by item level.
Note: One proc per minute assumed for trinkets with a hidden 45-second cooldown
+ Does not benefit from spell power, but does benefit from talents such as purification (2981). It can crit (4471 with purification)
++The theoretical maximum amount of mana that would be restored is 2,640, assuming you could cast 20 spells in 20 seconds and mp5 ticks every 2 seconds. Under real world conditions, ~2000 mana or less is more realistic.
For math, see this post.
* Five-minute fight
** Due to RNG, mana returned in any given fight is highly variable. Wear only when spamming Chain Heal.
Other Trinkets
[Darkmoon Card: Greatness] from
[Nobles Deck]
--90 Intellect version
--If use you Mana Tide when it procs, you would get an extra 1080 mana
--45 second hidden cooldown?
--If it procs once per minute, you would have 25% uptime, giving you the equivalent of an extra 75 Intellect
The proc would give 363 Intellect with Blessing of Kings, which would provide:
--2.18% spell crit (equivalent to 100 crit rating)
--54.45 spell power
--5445 total mana (68.1 mp5 from replenishment & 1307 extra from Mana Tide if timed properly but that's not always practical)