I've found the easiest way to fill the warehouse quickly is to play a level with Bears and box them in there before upgrading your warehouse -- it seems real obvious, but hey, sometimes we all could use a bump. :)
One of the 1st levels with bears to fill the warehouse is titled Powder Street 1. Powder Street 2 can be used, and even faster -- just don't bother doing the objective. Place the 1st two Bears in the warehouse, and then fill it the rest of the way with eggs. Just remember you will need chickens, grass, and water.
Have an addition from Matt DB87: You have to complete the level for the cheevo to 'POP'. ThX to Matt 4 pointing that out... it should B obvious -- but I should've mentioned in the 1st place. So he still deserves Kudos. :)
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