Also the mud patch part only gets about an hour of sun a day. That will be your biggest problem
Few things look nice all the year round but there are many things that look good in winter and quite a few that have more than one season of interest.
Are you looking for a small tree, bushes, or lower growing plants?
Some obvious starters which are below 0.5m (or slow growing enough that they stay below 0.5m for many years):
Hellebores - big "architectural" leather green leaves all the year. In early spring they have tiny flowers surrounded by big petal-like bracts in various shades of white, pink, purple, pale green depending on variety which persist into summer. Like shade
Epimedium - delicate oval leaves all year, and sprays of delicate yellow or pink flowers in spring. Likes shade
Skimmia "reevesiana" (the "reevesiana bit is important; others won't have berries unless you have a male and a female plant) - dark green oval leaves all year, clusters of highly scented white flowers in spring, followed by marble sized red berries which aren't liked by birds so persist - sometimes you have both last year's berries and this year's flowers. Tolerates shade
Ferns - some have leaves all the year round - Polystichum (shield ferns and holly ferns) usually do. There is also "Japanese painted fern" which is mainly grey and pink, but that dies down in winter. Ferns are great for shade.
If you've got a support (eg wall) that you could tie something in to, winter jasmine is great - little yellow flowers starting in about Ovtober and carrying on through to April. rest of the year it's just small green leaves - not exciting, but not offensive. I have it on the north wall of the house, so that's zero sun.
If you have room for a bush or small tree, there's a lot of scope for wonderful autumn colours combined with flowers in winter or spring, or instead, beautiful bark colours in winter, and possibly autumn berries