Lettuce is lovin' the rain, and I'm lovin' the lettuce.

A bin full of lettuce, picked about an hour go. Triple rinsed and ready to eat, sell, share...
My garden is mostly lettuce right now, but with all the recent rain and touches of sun, it's been a perfect year for lettuce, so I'm not complaining. Whether snipping outer leaves or cutting a whole plant a few inches above the ground, there are several techniques to harvest your lettuce that encourage more growth and production. Couple that with several sequential, 'staggered' plantings between April and September and you can have fresh (free) salad greens six months out of the year. Just let a few plants flower and go to seed at the end of each planting and either save the seed or let it self-sow.

If plants are flowering before you get a chance to harvest much, try pinching off the flowering stem as low as possible. If your greens are bolting, they're probably either too hot or stressed in some other way. Try placing an object or planting something to give them a few hours of shade each day--6 hours of sun is sufficient for most lettuce. Mulching the soil to help keep it cool is a good idea too, and it will protect your leaves from dirt splashes.
By the way, this romaine from my garden is naturally grown, no pesticides or synthetic fertilizers.
I think being planted among several other families of plants helped provide a diverse habitat that precluded any particular pest from bothering the greens too much. Oh, and I got lucky.