A crate is a common block in Junk Jack. When broken, a variety of items can come out, such as Nails, Widgets, Wood Planks, Seeds, Sprouts, and more.
These come in different varieties, with the more "armored" versions containing better / more loot.
Health Crates, which are less common, drop Bandages and/or Pills which can be used for healing.
It is highly recommended that crates are broken on your first day when not on peaceful.