Both suggestions are good, but the netting method works better, IME. The glue doesn't hold softies well, due to the slime issue. With the glue, it may look as though it took hold, but you may find it loose again days later. You can also take the loose shrooms and push it into a hole or crevice, for a 3rd option. That being said, I have not heard of shrooms dropping "new spuds". Shrooms usually move on the rock and leave a piece of them behind, and that leads to a new shroom. But I have seen an attatched shroom leave or drop off the rock. What shroom do you have?