Yes great find, BANNER really.
I live in Canada dug a lot of holes, there has only ever been a Victorian quarter in just ONE of those holes. A tough find indeed, any date. For comparison I have at least 9 Spanish silver coins for 1700's
As to have it graded, It's your choice, but I would not pay for an opinion especially on a mid grade coin, the market will decide it's worth should you ever decide to sell it. I hate coins in coffins. And it already has some scratches on it, the reverse, no doubt from when it first came out of the ground you gave it a small wipe. Which would "probably" make the grading company to say "cleaned".
To finish cleaning it I would just soak it in some warm water for a few minutes, and brush it with a small paint brush (that will not scratch it, and get the dirt out from around the letters/rim.)
BANNER vote sent.
Hi Rick, Thanks for the banner vote. Not sure I ever had one before. Wow 9 Spanish and 1 Queen Vic. I had no idea it was that hard to come by. It came from my yard in NY and an old school house lot for 1850. Found a few Canadian large cents in my yard too. Good advice on the grading