"Your cash ain't nothing but trash", do you know that song by Steve Miller 'the Spacecowboy'? Probably not, because that was way before your time. I must be getting old.
But to prove the opposite, here are 2 artworks that really are worth a lot of money and they are made from? Yes, trash!
"Some people call me Maurrricce", you should listen to that song, it really is quite pleasant.

Irving PENN - Cigarette butt

the first artwork is a photographic print by:
Irving PENN (1917-2009)
'Cigarette No. 37, New York'
Price realised GBP 175,000
Estimate: GBP 100,000 – GBP 150,000

link: www.christies.com/en/lot/lot-6191308

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Art Classes: Marcel Duchamp 'Fountain'

Marcel DUCHAMP - 'Fountain'

the second is an art installation (which was quite new at that time) by:
Marcel DUCHAMP (1887-1968)
'Fountain', it's made from a men's urinoir really ..
first bought by the Musée National d'Art Moderne in Paris in 1986. Schwarz's: Bought by an unnamed collector in 2002 for $1.08 million.

link:   www.pmmag.com/articles/85595-urinal-sells-for-1-85-million-at-art-auction

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Ideas in teaching:

Art at auctions is usually bought by people in 3-piece suits, with big money from museums and anonymous private buyers. Is that really what ART means?

Usually art museum and galleries are housed in sterile white spaces. Thinking along the idea of 'cash for trash', do you think it would be possible to make an art museum in a kitchen cabinet?