Wild Bird Seed - hanging bird feeders
Hanging bird feeders are preferred by some species of wild bird as they are used to feeding like this and can eat upside down or in any position. They are suitable for seed and nut feeding and come in a range of sizes and designs to hold different types of seed or nuts.
The clear plastic ones allow feeding from a hole at the bottom and contain small seeds, wire mesh ones are more suited to nuts such as peanuts [goundnuts] and the birds peck at these through the wire mesh. Check daily that the level hasn't dropped too low, and keep them topped up. Finches and tits love to hang feeding on the seeds, and sparrows will hang pecking peanuts for ages.
These are usually plastic with a small hole or holes at the bottom for the birds to take seeds from. They may have perches for the birds as well, and vary between quite simple feeders to complex feeding stations. There is always some wastage from these as seeds will spill out as birds feed and drop to the ground. But often ground-feeding birds will take advantage of this, so you may not have a problem of litter. I have seen hooded crows and magpies eagerly feeding on the ground under seed feeders on which tiny tits are gorging themselves above. Contrary to often believed myths about corvids [the crow family which includes magpies] that they kill small birds and nestlings, my observations are of all of them hunting for insects, seeds and anything else edible on the ground, and small birds seem unafraid of them. This is a hangover from the ignorant times when gamekeepers and farmers wantonly killed birds they considered pests; gamekeepers under the mistaken belief they kill game bird chicks, and farmers because they often eat seeds and therefore harm crops like wheat. That's where the word scarecrow comes from. They will eat pretty much anything, which includes dead or dying chicks if found as well as carrion of all kinds, providing a service to us all by removing what would otherwise rot and breed flies.
These are usually constructed from wire mesh, and the birds peck the nuts through the holes. Some are enclosed within an outer frame of larger mesh that is large enough to allow small birds to pass through and feed securely, but too small for squirrels to enter such as the one below. These are called squirrel-proof feeders, but sqirrels don't know this and will often try to get through the wire mesh, often bending and damaging it in the process!
There are is a wide range of types and designs here.
Feeders hung in trees or beneath vegetation are sheltered from the elements and from hovering raptors, so are much safer for small birds.
Hanging bread feeder
This takes a slice of bread and holds it securely so birds can peck from either side. It is best hung from the branch of a tree, or under a bird table. They come in various designs, some are hinged, while others have a slotted construction into which the bread slice is dropped.
Another good place to look for hanging bird feeders as well as other types of feeders for wild birds is ebay.