Cutting the roots may solve one problem but will open up another... Decay in the root system. Silver maple is notorious for shallow root systems, and they dont compartmentalize well when damaged. This could create bigger problems underground. My suggestion would be mulch. The roots arent the problem, its the mowing find a way to keep the mower from under the tree. If this isnt an option then you might add VERY LITTLE top soil to level the area enough to mow. And by VERY LITTLE I mean less just to fill the gaps between the high roots. The roots should still be exposed. (this is not ideal but its better than chewing up the roots with the mower).