From- The Defense of the Chair:
My chair is in Caer Sidi,
where no one is afflicted with age or illness.
Manannan and Pryderi have known it well.
It is surrounded by three circles of fire.
To the border of the city come the ocean's flood,
A fruitful fountain flows before it,
Whose liquor is sweeter than the finest wine.

From- The Voyage of Bran mac Ferbal,
The Land Beneath the Wave:

(Manannan says)
That which is a clear sea
For the prowed skiff in which Bran is,
That is a happy plain with profusion of flowers
To me from the chariot of two wheels.
The number of waves beating across the clear sea:
I myself see in Mag Mon
Rosy coloured flowers without fault.
Sea horses glisten in summer
As far as Bran has stretched his glance:
Rivers pour forth a stream of honey
In the land of Manannan son of LIr.
The sheen of the main, on which thou art,
The white hue of the sea, on which thou rowest,
Yellow and azure are spread out,
It is land, it is not rough.
Speckled salmon leap from the womb
Of the white sea, on which thou lookest:
They are calves, they are coloured lambs
With friendliness, without mutual slaughter.
Though but one chariot-rider is seen
In Mag Mell of many flowers,
There are many steeds on its surface,
Though them thou sees not.

From Cormac's Adventure in the Land of Promise:

There was a large fortress in the midst of the plain with a wall of bronze around it. In the fortress was a house of white silver, and it was half-thatched with the wings of white birds. A fairy host of horsemen were at the house with lapfuls of the wings of white birds in their bosoms to thatch the house...
Cormac saw a man kindling a fire, and the thick-boled oak was cast upon it, top and butt. When the man came again with another oak, the burning of the first oak had ended.
Then he saw another royal stronghold, and another wall of bronze around it. There were four palaces therein. He entered the fortress and saw the vast palace with its beams of bronze, its wattling of silver, and its thatch of the wings of white birds. Then he saw in the enclosure a shining fountain, with five streams flowing out of it, and the hosts in turn drinking its water...
He entered the palace. There was one couple inside awaiting him. The warrior's figure was distinquished owing to the beauty of his shape, the comliness of his form, and the wonder of his countenance. The girl along with him, mature, yellow-haired, with a golden head-dress, was the lovliest of the world's women. Cormac's feet were washed by invisible hands. There was bathing in a pool without the need of attendance. The heated stones themselves went into and came out of the water.
A shining fountain, with five streams flowing out of it, and the hosts in turn drinking its water. Nine hazels of Buan grew over the well. The purple hazels dropped their nuts into the fountain, and five salmon which were in the fountain severed them and sent their husks floating down the streams...
Manannan explains:
The fountain which thou sawest, with the five streams are the five senses through which knowledge is obtained. And no one will have knowledge who drinks not a draught out of the fountain itself and out of the streams. The folk of many arts are those who drink of both of them.
Hazels are trees associated with wisdom. "Salmon of Wisdom" comes from this and other stories. (Vitamin E good for the brain, I guess?)
Manannan's Crane Bag:
(From a poem in a collection known as Dunaire Fionn)
Aoife, who was in love with Ilbhreac, was turned into a crane by Iuchra, a powerful sorceress who was also in love with Ilbhreac. She flew to Manannan, who took care of her for the rest of her life - 2 hundred years- and then made a bag of her skin to hold his treasures.
Aside from this, Cranes were considered magickal beasts in their own right, guarding the gates of the otherworld, and ogham divination was done from looking at the shapes made by their legs as they flew. According to the Greeks, Palamedes invented the alphabet by looking at a flock of cranes that make letters as they fly. Old women were called 'cranes' in Scotland.)

Inside the bag:
The shirt of Manannan and his knife,
and Guibne's girdle, altogether:
a smith's hook from the fierce man:
were the treasures that the Crane-Bag held.
The King of Scotland's shears full sure,
and the King of Lochlainn's helmet,
these were in it to be told of,
and the bones of Asal's swine.
A girdle of the great whale's back
was in the shapely Crane-Bag:
I tell thee without harm,
it used to be carried in it.
When the sea was full,
its treasures were visible in its middle;
when the fierce sea was in ebb, the Crane-Bag
in turn was empty.
Manannan's cloak is the mist or fog, but "fog" was the fifth element in Celtic tradition according to the Colloquy of the Sages, and it represents, not so much "spirit" as "magic," as the stuff that makes magic happen. (Hence, Mists of Avalon, and that town, (what's its name?), that disappears and then reappears every so many years...)
Manannan gives Cormac a Silver Branch, with a golden bells (or a golden branch with silver bells, or a branch with silver bells). When it is shaken, it causes anyone who hears it to smile and be full of happiness.
He gives Cormac a cup that cracks in half when a lie is told, but reassembles when a truth is told.
Manannan could be pictured holding one of these branches, or the cup.