Manna and mature creation

4 Then the Lord said to Moses, “Behold, I am about to rain bread from heaven for you...13 In the evening quail came up and covered the camp, and in the morning dew lay around the camp. 14 And when the dew had gone up, there was on the face of the wilderness a fine, flake-like thing, fine as frost on the ground. 15 When the people of Israel saw it, they said to one another, “What is it?” For they did not know what it was. And Moses said to them, “It is the bread that the Lord has given you to eat...31 Now the house of Israel called its name manna. It was like coriander seed, white, and the taste of it was like wafers made with honey (Exod 16:4,13-15,31).

7 Now the manna was like coriander seed, and its appearance like that of bdellium. 8 The people went about and gathered it and ground it in handmills or beat it in mortars and boiled it in pots and made cakes of it. And the taste of it was like the taste of cakes baked with oil (Num 11:7-8).

To bolster their interpretation of Gen 1, young-earth creationists typically cite other examples of mature creation. The stock example is Jesus turning water into wine. Recently, John Byl mentioned Jonah's shade tree (Jonah 4). 

Manna is a neglected example. There's no natural process by which edible food rains down out of thin air. Presumably, the manna is a case of instantaneous creation.