YES - Vegetable and plant based left-overs (apple cores, plum stones, avocado stones, vegetable peelings, leaves, roots, pips, stalks, leftover vegetables (without butter in them) and so on. Also plain cooked rice and pasta(not cooked in stock or meat or dairy coated) Also tea bags, coffee grounds, stale bread and cereal, nutshell (except walnut shells)
NO - Meat & fish products - they will break down but will smell and can attract pests such as rats. Walnut shells (harmful to some plants)
MAYBE -Eggshells. They are often used if crushed but can also attract pests. If you do plan to use them, try rinsing them before crushing to removes the egg content.
YES - Grass cuttings, twigs, leaves, pulled up weeds, seeds.
NO - Plants with serious diseases (e.g. blight) which can survive compost process, spread through the soil, weeds that ae seeding and can take over the compost heap
TIP: Try to reduce the size of suitable garden waste by shredding or chopping to help the breaking down process.
YES - If taken from wood fires or from a wood burning stove , ash makes a good addition.
NO - Coal fire ash , coke fire ash or cigarette ash are a definite no as they contain materials which are toxic to plants.
YES - Manure - one of the finest ingredients you can get in your compost - (preferably well rotted) clean cotton waste, sawdust, chopped or pulped paper and cardboard (preferably without chemical inks) kitchen paper.
NO - Manure from carnivores as it can be damaging