There used to be a command for checking that (/is info) but here are the blocks that I know of:
Block of gold - 1.5 lvls
Block of diamond - 15 lvls
Block of emerald - 3 lvls
Block of iron - 1 lvl
Obsidian - 0.1 lvl
And these are what I remember from before the huge update, not sure if they've changed or not:
Cobblestone - 0.01 lvl
Skulls - 1 lvl
Wooden plank - 0.01 lvl
Enderchest - 3 lvls I think
And that's all I can remember
Also, you can now check by doing /is level so it updates your island level, place down 1 of a block, 60 seconds later do the command again. And if your island level doesn't change, then place 10 of that block. And if it still doesn't change, the level that the block gives is probably 0.01, but I'm not sure