Because Morells are a fungi they need to be with preformed organic material - something they can feed off as it breaks down, so just soil in your tub won't work.
I use partially broken down wood chip over a mix of soil, pine needles and mulch. I have pines and ash on the slope near me so am lucky in this regard.
I grow mine on a middle to upper slope, yours would need to be south facing, I'm facing the opposite direction here in Australia. If there are any live trees like ash, pine, elm. poplar, alder, apple - and oak and hickory where the fallen leaves form debris they feed off these, your morels are often found in the wild around these trees. My mixed forest area is also up from a small creek where they get a bit of humidity but not too much moisture. Give it another shot, hope this helps.