Melted Aluminum
Found some just like that in Mom's back yard in Verona - within 30 feet of a bullet, and under a local power line. I think these blobs may be the result of lightning strikes on nearby power lines and/or transformers - melting lines and fused connections on aluminum wires. These are, as mine was, good sized blobs of aluminum. Solder is considerably heavier.
Just my observations,
Selma Hunter