Do morph cards suffer summoning sickness
Playing creatures face down and turning them face up (commonly called morphing/unmorphing) has no effect on them having summoning sickness. Unless they have haste, they have summoning sickness until they've been in play since the beginning of your most recent turn, whether they've been turned face up or not.

For example, if you play a creature face down then immediately turn it face up, it still has summoning sickness until your next turn. Similarly, if you play a creature face down, wait til it no longer has summoning sickness, and then turn it face up, it still doesn't have summoning sickness.



Morph does have a lot of interesting rules associated with it, but a morphed creature is still a creature. Morph means:


  You may cast this card as a 2/2 face-down creature with no text, no name, no subtypes, and no mana cost by paying {3} rather than paying its mana cost.


There's nothing in there about having haste, so like all creatures, it has summoning sickness. (It can't attack, and its activated abilities with a tap or untap symbol in their costs can't be activated unless it's been under your control since the beginning of your most recent turn.)

Similarly, turning it face up has its share of rules, but all it really does is turn the creature face up:


  [pay the cost] ... turn the permanent face up. ... The morph effect on it ends, and it regains its normal characteristics.


It's still the same creature it was before, so if it already had summoning sickness, it still does, and if it didn't have summoning sickness, it still doesn't.