Holy crap! I could be the talentless hack whose family lived off the residuals for, “Happy Birthday to You” for generations!
Sorry, missed this. Didn’t do that much research, obvs.
Is 1845 late 1800s? If so, I’d just go to the Sutter’s mill area and sneakily pan enough gold to set up a store to sell to the gold rushers that will come three years later.
The sisters who wrote that and other songs were actually quite talented, and great educators.
The Summy Company (later Warner), which held the copyright (disputed) made money off the song, not the sister’s family. Even the sisters themselves made little off it, and they had no children, so no family to live off the residuals.
That area, oddly, had little gold.
It seems interesting that gambling, or betting, has been mentioned so little in this thread. Times have changed. 
150 years ago gambling and betting was much more widespread that it is today. Memorize the major events of the day and bet someone in town that Mr. Smith will go to Washington. That horse will win the derby, or whatever race is popular, etc. Start small and work up. Don’t stay in one place for long and you will be able to support yourself anywhere. As for gold, before you go memorize the location of future gold finds. Take just enough modern gold to keep you going until the betting starts to pay off, then head for the gold field only you know about. I don’t think Alaska is practical, nor Australia, but British Columbia should be doable. And if you search out the later finds in California you could skim off your share and still leave enough for the next guy to make history.
There have to be a lot of cheap factory produced items now that are similar to expensive items made by hand in the 1800s. Pocket watches and reading glasses come immediately to mind.
Screw the Prime Directive. I’m flooding the market with Pez Dispensers and View-Masters!
“View-masters” ? Oh, you mean stereoscopic photographs. That’s old news 
https://www.ebay.com/itm/123199279956
ISTM we had a thread like this awhile back and the consensus was that pearls offered the best ‘exchange rate’ for time travelers.
I thought of this thread when I recently bought a hard disk. Ok, they couldn’t use it in the late 1800’s… but damn, I just paid $99 for a disk that would have been worth $40 million in the late 1900’s.