Seedling pot made from an empty toilet paper roll. After germination, it can be buried directly in the garden bed as is; the roots will grow through the softened cardboard, and soil organisms will then consume it. Make sure to only use toilet paper rolls made from unchlorinated and unprinted cardboard.
edit: please check if recycling has a problem with chemicals or heavy metals in your country
the pots are made from the recycled cardboard part in the middle. pfas in tp are used to make the paper more easily flushable, so i doubt it's used in the part that wasn't meant to be flushed anyway. tp however wouldn't be a good material, because it's not sturdy enough and almost everytime bleached. however i saw that tp in some countries doesn't have the sturdy cardboard part in the middle and now i realise that you probably talk about the cardboard in paper towels because we are talking about the same material...
Oh yup, I meant the brown middle part in paper towel rolls!