As I recall, magical weapons can overcome damage reduction. If one were to attack an enemy with a wonderous item, like say attacking with an everfull mug in a barfight would it overcome an enemies damage reduction?
No, wondrous items such as an Everfull Mug or Piero's Pan of Flameless Frying wouldn't overcome damage resistance (magic) if they were used as improvised weapons.
Damage ReductionSRD is only overcome by magic weapons when the DR is specifically vulnerable to magic weapons and when the weapon in question has at least a +1 magical enhancement bonusSRD. Otherwise, magic weapons' damage is reduced just like any other weapon.
The only exception is if the weapon just happens to satisfy the conditions of the damage reduction some other way, of course; e.g., a silver Everfull Mug that doesn't have a magical weapon bonus would overcome damage reduction (silver) just fine, though not because it was magical.
The interaction of damage reduction and magic weapons is a frequent point of confusion in D&D 3.x, possibly since in the edition prior a creature immune to damage but vulnerable to particular material (like silver) was also automatically vulnerable to any magic weapon. When damage reduction was introduced in D&D 3.0 to fill the same rules function but without producing the same results, that it worked contrary to expectations caused problems for my group and others I knew. Then again, the frequent confusion might have nothing to do with edition changes – the DR rules are generally recognised as one of the more confusingly-written parts of the rules.
Despite the rules saying "no", your GM's game is your GM's game – they can tweak the rules as they see fit!