This is what I know about the origin of my family: the name Morell (the french spell it morel) supposedly derrives from the word Maure, which in french means Moore. The name suddenly appears in the 700's in the area of the cities of Tours and Poitiers, along with other versions of the same stem "Maure", like Maureau. An explanation of the sudden appearance of this name, and only in this area could be one event. Normally, names derrive from occupation, city or region of origin, thus evolving in a long time (along with the name of the city), or spread evenly across the country (following the spread of the occupation, like 'Schumann', which is a shoemaker). In 732 such an event can be found just outside of Tours and Poitiers. Karl Martell, called the 'hammer of the franks', defeats the Arabs, the Moores, outside those two cities. In conclusion, whoever was called Morel, Maureau, etc. had something to do with the expulsion of the Arabs from France, sparked by those seven days of continuing battle. What they had to do with it, whose side they where on, is not to determine without a doubt; yet there are still Morels found in Tours after the showdown, and arab names where not uncommon back in those days, so they probably fought on the french side. After that, the history fades, until the Morels reappear in 1572, as part of the Huguenot alliance in france. France, back then very katholic, had somewhat of a civil war beause of high ranking protestans. Anyway, big story, I don't think you want to hear the whole thing. Makes a good Grisham book though. Anyway, 23. of August to 24. of August that year there was the St. Bartholomew's night, supposed to be a huguenot-katholic wedding. That night though, the Huguenots where murdered, plundered, etc, and left the country in all directions. To Germany, where they settled in Berlin and Frankfurt, and are spelled Morell, to Italy, the northern parts, called Morelli, Morello, to England, where they are called Morrells. And probably to the Americas, but that I don't know of.
Anyway, that's how I was told, and I will tell my kids, if noone of you proves me wrong and gives me another hint on where the name could come from.