I don't know what these structures are. However, I suggest you to take a look on the website below. Maybe, you can find your answer in the cell image galery.
Joshua Charpentier These look like cell clumps/aggregates. The magnification would help get an idea of how big they are. For some reason, your cells did not attach well on the flask you seeded them in, which caused them to attach to each other and form these clumps. It can also be a mix of cells, cell debris & collagen. You can use a nucleus stain like Hoechst or DAPI to confirm if these are cells or not. A viability stain (eg propidium iodide or ethidium homodimer) would also tell you if they are dying in which case you should expect the cell debris to cause more clumping. I hope this helps!
Dear Joshua, I think that your cells are remarkably infected by the yeast or fungus, so neither of the depicted bodies are mesenchymal stem cells. You probably can observe the attached stem cells by focus altering.