I definitely have to look into that. I'm mostly interested in oak though.
I take it you perform a charging ritual with the coin then, first, Jenett? It just seems that simply plunking a random penny out of the pocket and uttering a quick blessing under the breath would not suffice.
Charging ritual? Nope. But at the same time, a bunch of my training includes how to do this kind of thing quickly and efficently. (I think anyone can do that, given some practice: the thing is that not everyone has yet put in the practice time.)
My process, when I use it (and that's pretty rare: the last time I personally gathered wood for a wand was, erm, 5 years ago. I've been given one since then, and I've gathered other materials for ritual work - flowers, tall-standing grasses for a Lammas figure, etc.) goes like this:
1) Figure out what I'm looking for.
2) Keep the intention in mind while I go looking.
3) Once I find it, charge an appropriate offering: this is a brief thing, but it's reasonably energy-filled. The physical process is rubbing or blowing or something similar on the offering, the energetic side is much like several steps of our standard circle set-up for charging/consecrating an item: brief but effective. (It's most like the techniques we use for charging/blessing the materials used in the blessing.)
Might take me 30 seconds. Might take me a minute. Depends a bit what I'm using as the offering: my own hair or my own spinning take energy charges really readily, because I've already invested a lot of personal energy in producing them. A penny, not so much (on the other hand, if I know I'm going out to do stuff that might involve offerings, I've probably been handling them as I walk. Same deal with a small river pebble or something.)
4) Put the offering down. Do the internal check to make sure I feel comfortable with the action, still. (a couple of deep breaths)
5) Do whatever harvesting stuff is needed. Do a final thank you, and go away.