Hi Dennis and Welcome to Permies,
So how much of a hurry are you to get those stumps out? You certainly could flush-cut them and bore holes into the remaining
wood to speed up decay. BTW, what type of trees were they? Were they some type of pine or some deciduous wood? The reason I ask is that each of those broad categories decay slightly differently. If they are pines or evergreens, I suspect that their soft wood will decay rather quickly on its own, and the bore holes will only help. If on the other hand they are some type of deciduous tree they might take longer to decay, but it might open other, interesting opportunities.
I am somewhat obsessive about
mushrooms, in particular Wine Caps. If this were MY
project (but it is not so do what you think appropriate) I would be tempted to leave the stumps in place and inoculate them with some type of aggressive fungus, my favorite being a Wine Cap because they are so incredibly aggressive and they leave behind lots of wonderfully fertile
compost. You could buy little peg spawn, drill a bunch of holes and push in the little pegs. Another approach would be to hollow out the center, add the chips back in but inoculated with the spawn (you could use
straw as well). You will want to keep it moist and it might take a year or so, but the fungi will really do a number on the old stump. Once the stump is thoroughly rotted, you can plant right on or near where the stump was located.
Anyhow, this is just an idea and if you have any further questions, please don't hesitate to ask,
Eric