The mulch I purchased last year had mushroom like things growing

Probably a fungus, which is what mushrooms are. They actually can be beneficial to gardens and flower beds and are usually caused by mild spring like weather and rain.

That's gold! Mulch it in....

Definitely a fungus

Obviously your mulch was contaminated with mushroom spores. Try sprinkling baking soda over the mushrooms and they will die off.

sounds like it got wet and you have the spores to bad they are not edible