There IS a console command to search for items nearby.
F5 -> "devcommands" -> find [spearname]
Spear names dont match exactly, but if you type spear, you can [tab] through different ones.

If you threw it flat its most likely still there. It is possible to throw one so far it disappears thou. The command has limited range, and spears can fly FAR so dont give up after one ping.

edit: vegetation quality to minimum while searching helps.

Also this IS cheating technically. But also throwing spear is super fun and you have to fail to learn so... your choice gl!