It occurred to me when I was looking for tree figurines for some of my home shrines, to go alongside statues like Artemis and Athena. At first, it was purely for decoration and symbolism. Artemis is Goddess of the forests and therefore the Goddess of trees; it's one of Her largest domains. And we all know the olive tree's reputation to Athena precedes it without introduction. So, originally, attaining the trees was not for the purpose of actual religious and spiritual engagement. But when I came across the beauty that many of us know as quartz trees, I soon realized how the gorgeous crystals that flood every branch could be used in the function of a prayer tree for the personal home altar.
I purchased one for that specific reason, on Amazon for only $13; nothing that broke the bank. I was stunned by its beauty and charm when it arrived, and also its convenient size. The tree comes fully equipped. There is nothing you need to do other than touch one of the crystals and recite your prayer, like I started doing today. As time goes on, even if you come to use the same crystal again for a new prayer, the energy can share the space with the old, or replace the old entirely if it's not needed anymore. This is far greater than just tying a note to something, because you are infusing your energy along with the prayer into the tree itself on your altar, and that prayer and energy remains there at work and in the attention of the Gods who come to the altar at any given time.
I hope you'll try this for yourself in your own practice. At least I myself find it wonderful to my daily rites. When issuing your prayer into the tree, you might try tagging something like this on the end of it:
I leave my prayer here upon my altar,
to live on in recitation to the Gods,
sent always with love, reverence and devotion.
Please, heaven, always hear my prayers.
In the Goodness of the Gods,