Although the common morel is Morchella esculenta, it is only 'common' by name: far more plentiful nowadays are the black morels, Morchella elata, shown above. How so? It's all to do with the fashion for mulching flower beds in gardens and parks using woodchip: black morels often erupt in vast numbers among bark and wood chippings put down the previous year.
Notice how the pits on the cap are in neat vertical lines - a distinguishing feature of this much-sought-after edible mushroom. The only nasty that you could possibly mistake for a morel is Gyromitra esculenta. That specific name 'esculenta' suggests an edible species, but in this case it's definitely not - or at least several people have suffered serious poisoning after eating it (even though some people report no problems after eating Gyromita esculenta, the false morel (also called the 'turban fungus'. So here is the enemy, G esculenta:
There are no pits on the cap of this poisonous species, so armed with this information I hope you will feel confident enough to gather and enjoy a few morels this spring.