A hand trowel is very useful for digging away accumulated dirt that covers a benchmark disk.

CAUTION: there are a lot of buried utility cables out there, and in most places you are not supposed to dig in your own back yard, much less along a roadside, without calling the one-call locator service first. That means any digging to expose what you think is a benchmark disk should be VERY cautiously done with a hand trowel, not a spade. Look around for warning signs or cable pedestals before you probe or dig.