If you are looking for food in the wild in the winter then you might want to start looking in urban gardens. Rose hips grow everywhere through Autumn and the Winter. In fact rosehips are quite easy to work with because the fruit is quite soft. You can make syrup, jellies and jams with rosehips quite easily. If you dehydrate them it is like making your own Vitamin C pill. You can also dry rose hips to make a nourishing and immune-system supporting herbal tea .
If you are bugging out in the United Kingdom and are looking for a wild outdoor growing fruit then look for mudlars.Medlars are little orange berries that are green to brown in flavor. These little berries are quite touch until November or so when the cold weather softens them. When soft they taste a bit like pears. They do have a stone inside that must be squeezed out. You can eat these straight off the tree, make jelly out of them or brew the berries like you would a tea and enjoy the Vitamin A and C that they provide.
A very common edible plant that survives frost and snow is Cow Parlsey. However make sure that you are very familiar with it because it really does resemble some other plants that can be quite poisonous including hemlock and dropwort. In the winter the bottom of the plant will seem dead but a little crown of leaves forms on top of it in the winter. You can eat the leaves as a salad or use it to flavor and add nutrition to powdered soups.
Sweet Ciceley is an aromatic relative of cow parsley that is also quite common and can be identified by buds of white flowers in the early spring.
Ground Elder is also a weed that easily foraged. You can find it below autumn leaves and snow. It was grown as a vegetable by the Romans and then fell out of favor. They look a bit like simple tree leaves but you can cook them up the same way you would spinach or any other thick green levy vegetable.
A similar winter leaf find is Alexander’s. These are plants with large shiny leaves that is found near coastlines. They have big tender pale green leaves that are delicious cooked in soup or stir-fried.
It is also possible to find fruit in the winter. Many red crab apple trees still have hanging fruit as late as February. You can find these trees growing wild everywhere, even in winter.
You can do a lot with crab apples which are very tart in flavor. You can make jellies or tea out of them which fully allows you to enjoy their high Vitamin C and A content. You can also combine them with brown sugar to make a delicious sauce.