I try to collect words and images, in case they end up being useful and perhaps making some future poem better. Often, these are the words and phrases that just seem to find me at unexpected/inconvenient times. But I also like to go out hunting for miscellaneous debris, every now and then. Field trips to grocery stores, museums, parks, and city streets can be productive writing retreats. You never know what you might notice if you're noticing.
It's a good idea to take a camera. It helps get you in the mindset of looking for images worth remembering and requires considerations of composition and perspective.
Here is a glimpse of yesterday's Thrift Store excursion:
Speaking of Thrift Store art: I love these "adding monsters to thrift store paintings" images:
But back to writing: where are some of your favorite places to hunt for literary materials?