Is there a sparkly/snuggly the crow equivalent trader in Bloodborne?
Solution 1:
In answer to your question: No, there is not an equivalent system.
However, you can use insight, the ingame currency, to buy items.
Sources:
"Items in Bloodborne are found in game [...] through trade with insight, or from chests. "
This site mentions nothing about traders, and a wiki would have mentioned so.
Solution 2:
There is no option to drop an item in bloodborne. I think that if there is such a thing as item trading it won't work like it did in the previous games.