That is the second cache of Farrells I have seen dug. The first was during the the building of the new Busch stadium in St.Louis. A fellow digger and member here hit a spot of fill, with nothing but pontilled Farrells in it. Hundreds of unused bottles,some whole but a lot were broken. I dug an area full of Mexican Mustang liniments at the same site. Weird how bottles turn up like that. I know of a couple caches of bottles being found that were unknown at the time of the dig,and remain the only known examples. As Rick says,you never know.
These bottles were puntied up on the blow pipes they were created on - you see it on puffs, flasks, etc. Note that the pontil diameter and thickness is always the same as the bottle top. I have stuck up pieces like this before - glass blower for 20+ years.