Help ! Something weird is growing on my lawn

Any Botonists, UFOlogists or Ghostbusters out there ?

I have 3 big piles of transparent goop on my lawn! They are about 15 to 20cm in diameter, are quite transparent and have been there for a couple of weeks (I’m too freaked out to touch them but I did poke one with a stick).

I’m hoping (really hoping) that they are just some sap fallen from the tree that sits in the center of the lawn.