Natural items as gifts
Hello! I'm an undergrad in the US in a field of biology. I'm going to be defending my honors thesis (as well as graduating) in the spring. I have been working on my thesis project since last fall, and my advisor has done a lot for me; in addition to helping with normal thesis things, he's advocated for me a ton in matters related to the project, and he's overall been very supportive. My project has additionally eaten a lot of money, at least as far as an undergrad research budget goes. My situation also warrants extra gratitude because my project falls outside of the lab's current focus.
It is pertinent to note here that this professor collects bones. I found an intact squirrel skull recently and have been going through the steps of processing it. Would it be okay to give the skull to him this spring after I defend my thesis?
Giving gifts seems to be a contentious topic, and all of the posts related to professor gifts that I have read have to do with store-bought items, or at least items of clear monetary value. Is there anything different about natural items (e.g. bones, insects, rocks, etc.)? Are gifts usually awkward? Would it be more or less awkward if it's a natural item? There's no clear consensus on what is and isn't appropriate or if gifts are appropriate at all. I know a card is a safe option, but I'm not so good with words. I was originally planning to just give a card, but when I found this skull, I thought he would like it, and I think that it may also help me communicate how grateful I am for his support and how much he's done for me.
Thank you!