Please see my previous post Black Morels of MN for some background information to this post
I think most of the morels I have found in MN are "yellow" morels. I don't think I have ever found any "black" morels, though I haven't always payed close attention in the past. I have found smaller, grayer morels that I have assumed to be a separate species, but they are probably actually immature M. esculentoides.
I looked at the records from the Morel Data Collection Project to see what species have been recorded in MN. There weren't many records from MN, and the only species identified was M. esculenta. I wonder if it is the only species actually found in MN; the other species I listed were just based on the written range descriptions. I suppose more appropriate titles for these two posts would be "Possible Morels of MN.