This is a kind of hawthorn tree and as you can see from the picture, it has lots of white flowers close together. You could call this masses of white blossom. There is a special saying that we have about it: 'Ne'er cast a clout till May be out'. This means never dress lightly until the tree has shown its flowers - don't wear a t-shirt or shorts until you can see the tree's blossom because the weather is too cold!
Another kind of blossom that you can see at this time of year is on the crab apple tree. The flowers are white and pink. The little apples are hard and sour but you can cook them adding a lot of sugar to make them into jelly - crab apple jelly.
Finally, another plant in bloom at this time of the year is wild garlic. This has white flowers and long green leaves. It grows wild in the woods and you can pick and eat the leaves. They have a slight garlic smell and flavour and can be put into soups.
May blossom By Rosser1954 - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=106585432
Crab Apple blossom by Eirian Evans, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=136536420
Flowering wild garlic by Evelyn Simak, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=136707261
Crab Apple blossom by Eirian Evans, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=136536420
Flowering wild garlic by Evelyn Simak, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=136707261