A signed doodle by Prime Minister David Cameron is going under the hammer for schemes run by the Cornwall-based Eden Project.
Mr Cameron made a sketch of a sheep with the words "THINKING OF EWE" written underneath.
Other quirky collectables up for auction include lyrics from the musical Evita signed by Sir Tim Rice, a piece by eminent artist Kurt Jackson, a visionary sketch of the future by Joanna Lumley, James Wong's childhood gardening book and artwork by singer-songwriter Seth Lakeman.
The online auction, which takes place between December 6 and 16, is based on the theme of inspiration.
As the Eden Project came into existence with the help of a drawing on a napkin and a spark of inspiration, the charity asked famous faces and organisations to show what inspires them, through a drawing, a favourite book or a memorable experience.
There are also special experiences on offer, such as wine tasting for six people at the historic London wine merchants Berry Bros, a spa day at Cornwall's Fowey Hall Hotel and a private chocolate and chilli tour for two at Eden.
In addition, the auction has a collection of unique gifts to choose from, including kegs of Sharp's Doom Bar Bitter, a luxury gift set from Neal's Yard Remedies and an exclusive Ultimate Chocolate Feast hamper from Eden.
Sir Tim Smit, co-founder of the Eden Project, said: "Inspiring people to believe they can make a difference and giving them the tools to do so is the key to all our futures.
"This is a principle that informs all our projects both here and across the country, which is why we've encouraged friends of Eden to share something that inspires them."
The auction will raise money for a range of Eden projects, from working with school, college and university students that visit each year, to engaging with socially excluded young people and helping community gardening groups to flourish.