Hey OP, let me help you out a little.  Here’s a close up of a peace sign done by Banksy that HAS been authenticated (sorry for thes**te pic).  It doesn’t look too dissimilar to the peace sign on your cardboard drawing.  So, never give up hope! (But don’t expect any help from Pest Control on this one).  To the forum, do these peace signs look alike?  YES OR NO?!

You will see a lot of replies, comments, jokes here but the bottom line is:

It is totally unsellable without a COA

Ive already joined...his mom is an amazing woman-- thinking about a gift for her 15 year olds sons birthday that is a month and a half away while high smoking a spliff with Banksy.

I would never doubt the word of someone that was carried by that amazing woman. 100% authentic.

I love your mom.

This is the advice your looking for. It is you cannot sell it publicly for anything close to what you'd want for it without a COA, which you CANNOT get through pest control (I thought they did authenticate gifts if it comes form the original person gifted, but maybe not with OGS?), so you only option is to compile the information you have.

It may sound silly, but an affidavit from your mom is better than nothing, have it explain how she came to meet Mr. B and the prov of the piece. If your mom was reputable enough to be a known associate of the artist that may be enough to get you into an auction. But your best option is to sell it someone you know who knows your mom and your background with the artist and therefore is comfortable with authenticity.

Why was it specifically denied by PC? Make sure to get the precise wording. If its akin to "we cannot authenticate gifts" then your likely ok to move forward with a sale, but if it was an outright denial you should probably get them to elaborate in writing. If they came to the conclusion that it was not authentic, even if they are mistaken, its a death sentence and you should just keep it as even though you may know its authentic, it would be unethical to sell it if PC expressly deemed it inauthentic. Bottom line, just make sure you havesomething in writing about why it was denied.

Good luck...assuming your story is genuine.

give the guy the number for the Sincura Group.... lovely people... and will defo take it from you.

Nice little piece but as many have said without PC provenance it will be difficult to sell for something that in the short term would be worth your while. No reason to disbelieve the back story and aesthetically looks correct. Nice little rat and found the tongue in cheek Hallmark copyright 2008 symbol amusing and in keeping with the artist. Honestly one day when money is not an issue, a few years post graduation, you might well regret selling this for the relatively small sum of money you could obtain right now. Sentimental value often grows over time whilst access to money sometimes gets easier. Good luck in whatever you choose to do.

PC - as for sign roads - will never send a COA for this kind of artwork. They are authenticate prints and canvas with references.
Anyway this drawing does not take 10 minutes, but seconds.

i'd keep it. its a rad little token made just for you. wouldnt mean the same to anyone who bought it. 

I totally agree with the posts on here about not selling this card. It will become a brilliant family heirloom that can be passed down the family over the years to come.

Document what you can from your mum, put it in a sealed envelope and frame it behind the card. Your kids (and even their kids) will have a personal connection to it that nobody else can possibly have.

That's got to be worth more than a few quid right now...

In that "un authenticatable" doesn't mean unauthentic?

But according to the OP, it was PC that said it was "un-authenticatable"(hyphenated), not him.

Rats are his speciality, hands and feet not so. He can knock out a rat in any circumstances 😂