I agree with Ecnerwal's short but correct answer. This looks like a grafted tree due to the swelling near the base that has suffered repeated damage from a hard object like a mower.
Putting mulch around the tree is good to stop the grass competing for nutrients but do not have the mulch laid deeply next to the trunk. Retaining moisture next the trunk can help fungus grow.Pull the mulch back a few inches around the trunk.
The wounds are healing but will be a source of weakness should this tree get to a large size.
As the trunk does not look to be more than a few inches in diameter perhaps this is the time to ask yourself if you want to invest a long time in a tree that is described as
"should be saved for planting in wet areas or where nothing else will thrive. Roots often grow on the surface of the soil making mowing grass difficult under the canopy. They also are aggressive, growing into septic tank drain fields and into broken water and sewer pipes. It is also hard to plant shrubs and other plants beneath the branches due to the dense root system."
Another article points out the issues I have seen with silver maples:
"Unfortunately, this species also has several liabilities as a landscape plant: weak wood that easily breaks during wind and ice storms, sensitivity to high pH soils and deicing salts, and prolific seed production and germination that creates a weeding issue in gardens. The root systems of silver maples also grow vigorously and superficially and can penetrate drain tile and sewer lines, raise or buckle sidewalks, and make mowing difficult. "
The wood is weak and with the existing issues if it was my tree I would remove it and plant a tree that was more suited to the urban environment.
