From what I understand, the sign says Sneed’s feed and seed (formerly Chuck’s), I am assuming it means Chuck owned the seed and feed store. Does this mean it was Chuck’s Feed and Seed? I don’t get it.

It either means it was formerly owned by Chuck (since it's a cartoon)
Or
It means it was formerly known as Chuck's the previous company's name. Either the name change was due to a merger, a buy out, acquisition or corporate internal arrangements

Heartbender:
It either means it was formerly owned by Chuck (since it's a cartoon)
Or
It means it was formerly known as Chuck's the previous company's name. Either the name change was due to a merger, a buy out, acquisition or corporate internal arrangements

But why would a feed and seed store have a corporate acquisition? Maybe the feed store is a chain or something?

Is this Chuck a recurring figure?
Perhaps it is referencing a previous episode?

old name (chucks feed and seed) doesn't rhyme but sneeds feed and seed does, may be just lucky that guy with that name buy the store

pekkaan13:
old name (chucks feed and seed) doesn't rhyme but sneeds feed and seed does, may be just lucky that guy with that name buy the store

Do you think maybe Sneed was eyeing Chucks property?

sneed

The sign is a subtle joke. The shop is called "Sneed's Feed & Seed", where feed and seed both end in the sound "-eed", thus rhyming with the name of the owner, Sneed. The sign says that the shop was "Formerly Chuck's", implying that the two words beginning with "F" and "S" would have ended with "-uck", rhyming with "Chuck". So, when Chuck owned the shop, it would have been called "Chuck's F*ck and Suck".