Try this
## Create some data set
set.seed(1)
my.data <- list(df1 = data.frame(Y = sample(10), X = sample(10)),
df2 = data.frame(Y = sample(10), X = sample(10)))
FitWeibull <- function(data){
my.lm1 <- lm(data[[1]]$X ~ data[[1]]$Y)
my.lm2 <- lm(data[[2]]$X ~ data[[2]]$Y)
par(mfrow = c(1, 2), pty = "s")
plot(data[[1]]$X , data[[1]]$Y)
abline(my.lm1)
plot(data[[2]]$X , data[[2]]$Y)
abline(my.lm2)
}
FitWeibull(my.data)