Yes, mistletoe does grow in the trees, but not necessarily way up at the top. It's a parasite plant, and will grow where it catches a good hold on a tree - usually in the crotch of two limbs (be good, Spaw), and usually high, but not at the top. Just look for a dark green bush (I said be good, Spaw) in an otherwise emtpy tree.

I lived in Indiana for a number of years, and never saw any mistletoe there growing (that's not to say that it doesn't tho). But when I lived in South Carolina I saw quite a bit of it in the old oak trees. In SC, the traditional way to harvest it is with a shotgun - blast away at the bush, and pick up the sprigs off the ground. If I still lived in SC I'd send you some, but I moved from there a few years back.

If you do manage to find some growing, keep in mind that the berries are poisonous. Which is why they put plastic berries on the live plants they sell.