We talking one, two, a few... by the roll, bags??? They certainly sell bags and rolls of junk silver. Give them a call: (800) 375-9006
They have a $1,000 minimum for purchases. I was not sure if Washington Silver quarters were something they accepted.
They have to get em from somewhere, collections, hordes, old rolls, Mint bags, junk collected from individuals and dealers... give them a call to see. We have no way of speaking for their policy in this matter here and don't know how much you're talking about selling to them to base it on much more speculation.