We have rubbery mushroom type fungus on red maple
These are small with leaves which roll up and you can unroll them, but they spring right back again. They are brown in colour and only small as yet. The tree is in a bed against the garage wall in a south facing garden. We have red and green Japanese maples further along the bed, which are thriving and have been for many years. They are not on the roots, but in the first foot from the ground.
This article might help you: https://www.gardeningknowhow.com/ornamental/trees/maple/maple-tree-bark-disease.htm
You also could take a sample of the growth to a local extension service; They might give you more specific information. This link will help you locate one: https://www.gardeningknowhow.com/extension-search/